Not good for people who play 100% offline. This is what kept the game alive for me in GT5. Arcade used to be a huge thing, but now they killed it by taking fuel/tire consumption out. Playing online is not an alternative since it's not nearly as fun (again for some, me included). You first have to look for a lobby, or make your own, you don't know what kind of people will be in that room, and almost always interacting with people isn't a pleasant experience. I prefer the dead A.I, even though it needs to be improved drastically.
Right now I'm waiting for an update that might bring this back and also fix the blind A.I. In the meantime, I'll try and find a reason why to keep playing, even though it's getting harder day by day. Thankfully I have other games to keep me entertained.