If You Can Overcome the Tough Gameplay, A-spec is an enjoyable game
One thing though is that Simulation Mode has one flaw, and I can respect that you start with little bit of credits to get the only good cars, but there are no used cars in the game, you have to buy new cars. It's a tough choice, but make it right, and you can start off well. However, sometimes the game tends to cheat at points, letting all the other vehicles reach better accelerations at times, but it is still very fun. I just wish the used cars were in there. But the idea of starting with $18,000 was a bit unusual because in all the other ones, you start with $10,000. But that's okay.
Overall, it's a fun game, and should be played. Play good and save that good data for a new Gran Turismo 4 game for a head start. It's a good and fun game.