Well, it's finished downloading and after play a bit I have made the decision that, no, this isn't worth buying. You are better off waiting for SuperCar Challenge.
You can buy the full pack, or buy the items seperatley. I did the former. Everything you have bought from the pack, you can go and buy for no credits on the game, so I was pleased with that, as I've seen a couple of games where you can buy a pack and then you have to unlock it in the game. (Midnight Club Los Angeles, I'm looking at you.)
I don't think the full pack is worth buying overall, only if you like everything that comes in that pack. However, there is one item that is worth buying. It's the amazing machine I call the P330 F4. This classic Ferrari is a beast like no other, and is really a joy to drive. I bought the whole pack, and now sort of regret that, I should've only bought this awesome car, it really is a marvel to drive. It's flawless. And fast.
Yeah, so if you like everything that comes in the full pack, then go ahead and buy it (also remember all of this will be in SuperCar Challenge as well), but if not, get the P330 F4 seperatley, because that is awesome, and wait for SuperCar Challenge.