Let me just start this off with saying I am a huge fan of the Gran Turismo and Need For Speed series', but have thought for a while now that it seems PD have become complacent to the opposition.
I'm not looking to flame, troll or generally start off an argument, this is simply my personal views on a number of aspects of the two games.
The comparisons
Cars
GT5 - 1000 plus
NFS - 150 plus
Gran Turismo has well in excess of 1000 cars (including a vast quantity of duplicates) whereas Shift has to struggle along with around 150, if you count all the DLC packs. Now, this would be a walkover section for Gran Turismo, if i weren't for one key aspect - Consistent levels of quality, as the bulk of this number are ports from previous generation releases.
Now some will argue that Shift 2 having a lower car count would mean that they could focus a lot more time on getting those cars right, and therefore there shouldn't be a comparison. Well, yes and no. When you take into account that of the 1000+ cars in Gran Turismo, only around 280 are "premium". Of these, there are so many duplicated models which just have engine differences or slight visual differences, so this figure could easily be dropped to below 200, so we're on the similar lines as Shift already.
Winner - Draw
Circuits
GT5 - 30 unique circuits, 90 overall including time and weather changed models and reversed running variants.
NFS - 35 unique circuits, 86 overall including recognised alternative circuit layouts.
This is where things get very interesting, GT5 seemingly has this one covered too, but peel back the skin and you'll see that this is a fail too. GT5 counts the reversed run of a circuit as another individual track, so the track count is almost doubled. Then there's the time shifting circuits, also counted as separate "new" layouts, despite the non time change circuit being added. Also using this method are the weather effected circuits, which also have non-weathered circuits alongside them. All in all there are around 50 different circuit layouts when you remove the reversed and duplicated for effects circuits.
Shift has no duplication curcuits for reversed running, weather effects, or for time shifts so each of the 86 or so variations are different and, more crucially, recognisable as completely different layouts.
Winner - Need For Speed Shift 2
Overall visual representation
GT5 - 9/10
NFS - 8.5/10
There's no point weighing up the odds here really, discounting the "standards" from the picture GT5 has the best overall looking presentation of any racing game to date. There are still huge stumbling points, including (but not limited to) Trees that have no body to their appearance, reflections of the road surface visible on the interior of some cars as if they have glass bottoms and the crowds are made seemingly using flat 8 bit .gif files that wouldn't look out of place on a Sega Megadrive.
Shift 2 falls slightly below the visual level, but they're getting mighty close on a number of levels. The highest point of Shift is it's sheer representation of speed, which actually looks like the speed being displayed on the dashboard. GT5 seems to have lost any real sense of speed, with 200mph looking more like 50mph sometimes. If there's a Shift 3 it WILL look better than GT5, without a doubt.
Winner - Gran Tursimo 5
Career Mode
GT5 - 6/10
NFS - 7/10
Both games have a progressional career mode which unlocks new challenges, higher level cars and more competent opponents, but NFS has a much better level progression than GT5. With GT5 you just need to have a more capable car, and little skill, to win some events, but with NFS the opponent cars will be more closely matched to the one you bring to the fight.
Winner - Need For Speed Shift 2
Opposition AI
GT5 - 1/10
NFS - 9.5/10
This has been a major failing of the GT series for a long time, and really needs to be fixed if the series is to be taken seriously for much longer. The AI are sometimes docile, will not deviate from a programmed path and don't seem to recognise your track position in relation to themselves. There may as well be two metal rails dug into the road along the racing line, as they will not deviate from it even if you force them off the track. Put one into the gravel traps and he'll sit there and wait for all the cars to pass before rejoining the circuit and in some cases I've been driving behind them for position and have seen them actually brake and let me pass. It gets even sillier, at Route X I've had the AI brake on the straight, despite being on a completely straight and unobstructed road.
Shift 2 has an excellent AI system, who will actively try to avoid collisions, or sometimes even cause them. Will fail all by themselves under pressure and put themselves of the circuit and will fight back as hard as you give them. This win is a no brainer,,,
Winner - Need For Speed Shift 2
Effects - Visual
GT5 - 5/10
NFS - 7/10
A problematic one for comparisons, as Shift has no weather effect circuits. (to date) Gran Turismo does however have weather effects but the implementation and appearance of them is sketchy, at best. All the after-effects in GT5 seem to be incorporated into the base layer of the car, so the pixelation evident from these effects have a direct negative effect on the car beneath, to a degree where the car could be recreated using lego bricks.
Shift 2 doesn't suffer from this problem, the smoke effects are so much better than in GT5.
Time shifting though are where GT5 gets some points back in this category, as the times can be varied and the effect is pretty good, but not perfect. Some lighting changes will appear "poppy" and jumpy, with the transition from light to dark being especially noticeable. Shift 2 has 3 time variants for every single circuit and layout, with Day, Dusk and Night representations.
Winner - Need For Speed Shift 2
Damage
GT5 - 2/10
NFS - 10/10
GT had promised such huge levels of damage before launch, but failed to hit their targets, with mere visual damage that belies the incidents that led up to them. At best you can knock off the doors and have the hood and trunk flap about, but even then there's only a selection of cars that this can be achieved with.
Shift 2 has the most devastating level of damage representation I've seen in a game yet. Every panel can be ripped from the shell and wheels can fall off. I have hit a bump so hard that one of the fron wheels fell off and took off down the circuit in front of me.
Winner - Need For Speed Shift 2
This review is getting really lengthy, so I'll get these over with quickly,,,
Handling
GT5 - 8.5/10 - Clean and intuitive, easy to master.
NFS - 6/10 - Fiddly at times, takes more effort to perform at the same level, but is more rewarding.
Winner - Gran Turismo 5
Sound
GT5 - 1/10 - Cars have woefully bad exhaust note recreations, sometimes even the wrong sounding notes completely. V10 engines using duplicated V8 noises is just the tip of the iceberg. There's also too much transmission whine when compared to the exhaust level, and no way to refine the levels via audio sliders. Dump valve sounds and over-run are completely inaudible, and presumed not to exist.
NFS - 11/10 - All the cars retain their distinctive exhaust charateristics, even after tuning. Dump valves and turbo chatter are also clearly audible, as is the correct level of transmission whine and even over-run and backfire sounds.
Winner - Need For Speed Shift 2
Solid Objects
GT5 - Not subject to the laws of real physics, concrete and steel can be driven through given enough grip and a little patience.
NFS - I've not managed to drive through anything yet.
Winner - Need For Speed Shift 2
Extras
Livery Editor GT5 - No NFS - Yes
Engine Swaps GT5 - No NFS - Yes
Nitrous GT5 - No NFS - Yes
Winner - Need For Speed Shift 2
Styling and Tuning
GT5 - A concise but clear tuning system means that every detail you change has an effect, but you know exactly what that effect should be.
Styling is where GT5 falls down, as the aftermarket kit is very limited to varying degrees. Some you can fit just the aftermarket wing to, where other can essentially have a full makeover. 17 full race conversions, seriously?!
NFS - The tuning model of the game is instantly confusing, as there are no rating representions to use for guidance (Kg/mm etc) so I find myself adding the parts and then running them in theor default settings, which is obviously less than ideal for best performance.
Styling is where NFS takes the fight back, 3 levels of road based visual modifications for every single car and then the full racing conversion for all of the road base models.
Winner - Neither, a draw.
Overall winner - Need For Speed Shift 2
Whilst the Gran Turismo series set the benchmark for their PS2 games releases, PD seem to have sat back and relaxed, where all the other developers have progressed and improved their output.
Gran Turismo 5 is very clinical in it's feel and approach, to a degree that sometimes removes the fun from the experience. Shift 2 puts it back in, with the constant threat of being dumped into the barriers by an over-zealous Gallardo driving AI and you losing every wheel on the car. Sure, the physics of the games are dramatically different, but again GT feels clinical and uncommunicative, whereas Shift has a sensation of accomplishment that you cannot get from GT5, no matter how hard you try. The drift model in Shift is more readily mastered than the "stick some wooden tyres on any car" method that GT5 seems to require, and is ultimately more user-friendly. It's much easier to control a slide in NFS than it ever has been in GT.
Both games have their huge plus points, similarly they both have some big minuses too. All in all I'd say keep both, as you'll get burned out with one and move to the other, then back again.