The most underrated game.
The reason I say it's the best GT to date, is because the gameplay and physics are by far the best of any GT game so far. The game is just so damn fun, and it just gets better and better as you play. It really starts to pickup once you get past level 14 or so. And there's so much content and things to do in GT5, if any game is worth $60, it's GT5.
The graphics in general are still eye popping good. Premium cars, even in-game, look very good. I think PD should have trimmed the fat and left some of the ugly standard cars out. One disappointment for me, is that one of my favorite tracks (Laguna Seca) looks bland in certain areas. I think PD could have done a better job modeling that track.
I honestly don't understand how any racing sim fan or car buff could be disappointed with GT5. It is a car lovers dream game. So many expensive and exotic cars that can be taken out on the track, and you can even view replays and open photomode and take pictures from pretty much whatever angle you want.
So with that said, I think that if you're on the fence and you're a previous GT fan or car lover, you will NOT be disappointed with GT5.