Although its not a perfect 10, GTA IV is the best in the series, and one of the best games Ive ever played.
Gameplay- The gameplay is the standard GTA style mix of shooting, driving, and a bit of stealth. The things they have added to the combat add a lot to this game though. The cover system is great. Its not like Gears Of War, where you have designated areas to take cover behind. Anything can be used as cover. This makes the gunfights more technical and adds another layer to the fighting.
The new targeting system is excellent too. You can either hold down L2 slightly for free aim, or hold L2 down all the way for auto aim.
The driving is pretty good too. Lots of people have complained about it being too hard, but I dont think realism is a bad thing at all. One major thing they left out of GTA IV though was the car customization. It was kind of an ancillary thing to have, but it still added another cool element to the game.
The AI is pretty advanced in this game. The characters and NPCs really interact with each other very well, immersing you int he game that much more.
Graphics/Sound- The graphics are decent by next gen standards. But you have to consider the large scope of land in this game and the sheer amount of content that goes into GTA games. I would rather have a thrilling game that lasts 40 awesome hours that has decent graphics than an 8 hour game with fantastic graphics. The graphics are suitable and are good enough. My only complaint with the graphics is that when set to default, the game is waaaaay to dark. you have to set it just right for your tv.
I give the sound a mixed review. The character voice overs are excellent. They are full of emotion and even the pedestrians on the sidewalk talk and sound excellent. One complaint I have about the voiceovers is that so many of the characters are incredibly hard to understand, so I had to put the subtitles on. The sound effects are really good as well. The soundtrack isnt that great in my opinion. I really liked how Rockstar put 3 talk radio stations in the game. I like listening to the talk radio.
My main gripe with the soundtrack is the rock and rap stations just dont have a lot of music in them, and there is too much techno and rave like crap. I wish the music was more cohesive like in Vice City.
Multiplayer- I think the multiplayer is excellent. I have played all the modes, and I really like the modes. I havent experienced lag at all. My main complaint with the multiplayer is that the servers are down so much of the time.
Fun/Value- This game is incredibly fun. There are so many visceral gunfights, crazy car chases and high octane action sequences. This game will take you around 35-40 hours to complete, and that is with minimal side quests done. The multiplayer has great value as well, adding a lot to the GTA experience.
I think if you can handle all the swearing, sexual content, drug use and extreme violence, GTA IV is one of the best games you'll ever play. Although it isnt a perfect 10, its still an awesome experience.
Pros- Excellent mix of shooting and driving, Awesome new features like the cover system and doing activities with friends, great characters, great sound and detail, decent graphics, fun multiplayer, great value.
Cons- Bad radio, missing some features (car customization, more weapons, clothes, properties to buy), multiplayer servers still spotty, and the freezing issue plagues many PS3 users.