I was going to sell the game, but after reading some of the posts, I am not ready to right it off yet. I am very used to GT5, so maybe it will take time to adjust to F4 physics.
Forza is just one of those odd games you just have to try first. If you've never tried the series before, you can't tackle racing like you do in GT5, or your favorite sim, or even real life, or it's going to frustrate you. You have to practice it more than any racer I've ever encountered, because it's just it's own creature. In some ways it's very realistic, but in others it's just weird, and you have to adjust to what it demands. According to Scaff, the MS FFB wheel is dandy, so I'd suggest finding one if buying a Fanatec is out of the question for a while. I can't enjoy racers without a wheel controller of some kind anymore, and it is a big help with a game as finicky as Forza.
I was wondering if someone would bring up Shift. One of the mods over at Forzacentral told me where the team had come from, and they mentioned several game companies such as Crystal Dynamics. But a core group had been hired away from EA's Need For Speed team, and Forza has always had some of that flavor in it.
If you have it, I'd suggest you keep at it for a couple of weeks or so, and try different things, even different views. I've gone back to my "hang gliding" view and this has helped quite a bit with the R Class cars. The bots are annoying as hell sometimes. They brake like GT5's bots do, and ram you like GT4's bots do, and will throw you off the road like Forza 1's bots do. And I'd mentioned that some of them drive like Jeremy Clarkson after he's had a few, which is rather unnerving when you're in a "professional" race with high powered race cars, and some bots are driving like stoned teenagers!
You also should look at the Livery Editor, which is the big reason I keep coming back to Forza. Being able to race mod any car in the game, even to swapping drive trains on many cars, as well as being able to paint all the race cars, is simply too awesome for a car artist like me. And there are a few very nice artists who make incredible designs for sale if you just can't get a handle on it, but want a different look for your car. And there are decals for sale, many great ones for free, so you aren't stuck with the skimpy list T10 gives you. I especially like the wealth of real racing plaques and league badges offered in the Storefront. Of course this means you need Live Gold, but you should be able to find some deals on Live subscription cards online.
I'm getting back to GT5 today because I need a break from tense, belligerent, uncertain racing. Besides, I've been caught up too much in getting through Forza's seasons and haven't even tried GT5's marvelous DLC yet!