As an avid fan of racing games and especially the GT series, it pains me to tell you that GT4 is dissapointing.
I'm not trying to say GT4 sucks, it's still a very realistic racing sim with more cars than ever to drive. There is just so many places they could have really improved upon but choose to ignore.
First I will talk about the positives. Graphics are expectedly stunning, especially the new tracks which have new scenery that looks nearly photo realistic. The 1080i widescreen HDTV mode is a great addition that I was able to take advantage of and it significantly improves the detail and clarity of the graphics. This is easily one of the best looking PS2 games ever but it still suffers from aliasing and shimmering that plague almost every other PS2 game. Still, it is quite a testament to the endearing PS2 hardware to be able to render cars that look almost as good as the models in next generation systems like the Xbox 360. One problem however is that the graphics switch to an ugly interlaced mode many times when racing on the newer tracks in order to prevent the framerate from dropping. Luckily it doesn't affect gameplay.
This time around there are over 700 cars spanning the entire history of the auto industry, lots of new tracks, a few new car upgrades and lots of photo-mode and auxilary features which don't really add much value to the game.
Shockingly, the biggest problems the GT series had from the very beginning STILL remain, primarily the horrible car AI, non existent car damage and absolutely no story elements at all.
Although GT4's car driving physics are still second to none, any improvements they've made can't be dedected. It is still extremely fun to drive realistically modeled cars from the real world but the game gets old really fast when you feel like you are always racing by yourself. The other cars have no idea you are there, they simply don't react at all to anything you do and will smash right into you in a corner if you are in their pre-determined driving path. This kind of dead-beat AI really hurts the game and is inexcusible when this is the forth game in the series.
GT4 is much more challenging but the challenge is added in a very annoying way. Instead of making the AI smarter and more competitive, they simply make it very hard to make much money. Most of the time you enter a race series, you're up against better cars with tons of upgrades. The only way you can hope to compete is to spend loads of cash upgrading your. Once this is done you can simply dominate and win every race easily.
The problem with this is that the strategy for progressing in GT4 is mind numblingly boring. Buy a crappy car because you can't afford a good one, race the same events over and over until you build up enough cash to upgrade crappy car, then take on the new race series. Rinse and repeat. I would much rather be challenged based on my driving skills against the AI than my mechanical skills and knowing just which gear ratio I need or what the hell a limited slip differential is supposed to do. Don't get me wrong, I love upgrading the cars but I just don't want it to be the central means of progressing. Another problem is that you cannot see which cars you might compete against in an upcoming race series until you buy the type of car called for and try your luck. Most of the time you find out the car you just bought is completely out-classed and have to spend tons of money upgrading it or buy another car causing a lot of wasted time and money. That's just not fun. I've never had this problem in GT3 but because Polyphony seems to be incapable of programming any decent AI, they boost the challenge in an artificial way that is no fun for the player.
I really think they wasted too much time on modeling more cars, adding the b-spec "manager" mode and photo modes. These things add very little to the series and the main issues were not addressed. I feel like the series is going nowhere, it's completely stagnant and that saddens me when I know that they have by far the best driving physics of any racing game. If Polyphony doesn't move the series forward in the obvious direction with GT5 on the PS3, I will not be buying their product, simple as that and I'm sorry to say Forza is better than GT4 even though it's physics are a bit wacko. It is just a better all around package. Polyphony, WAKE UP and give us the kind of racing game we know you can make.