Forgive me if I'm way off-base here but I think the reviews seem a little harsh considering the main point of contention is the fact there is no 'Career' mode, thus no achievement.
Why?
If you really, really think about it racing games have a career mode for one thing...to accumulate cars and unlock tracks.
From what I have read it seems all tracks are open right from the start, which is better than having to race a predetermined number of races to unlock tracks. The variety is there from the start.
Secondly, as with any other racing game, you still accumulate credits and purchase cars. Now, to me, that sounds like any other racing game.
A different mechanic yes...but it is that far away from the norm? Nope.
I'd just like to add that the CVG review pointed fingers to the fact players aren't able to buy any car...they have a selection to choose from at different intervals. This is the whole structure of GT PSP, is it not? That's why there is a trade function in the game. For example if people miss a great selection of Ferrari's and find someone else racing one online they can trade. In other words THAT'S THE WHOLE POINT OF THE GAME. Certain cars may be rare compared to others.
Shame about the A.I., though.