Sure there was a lot of hype surrounding this game, but to be honest just about every bit of it was warranted!
With that out of the way, let me just say that something that people don't realize is the technically amazing achievement this game truly is. The reason many wouldn't even think that is because its not the best looking game on either system (360 or PS3) there are better looking games that even came out some time ago (Gears of War; xbox 360) but none of those other beautiful games pull off as much technially as GTA IV. With the high quality graphics, the sheer amount of dynamic and background loading content and the life (and death) and attention to detail is just not seen in other games to date. There is so much to do, single or multiplayer, Rockstar is really the King of Sandbox. And for the most part they do it so seamlessly.
Technical achievements aside the game is damn fun too. Sure I'm only 30% through the single player campaign so I have a ways to go and probably some bouts of frustration along the way as well, but with what little I've seen and the great joy my friends and I have had in Multiplayer so far this game is a must play for any mature gamers who were fans of the series in the past or just want to enjoy some great run-n-gun action and story.
Top notch voice acting - I've only run across one voice/character so far that I thought was kind of a sub-par performance. Quality writing and dialog and such a seamless blend of action and entertainment. I am a big fan of Mass Effect and I'd say, although its a completely different genre, this game also shines in some of the same areas that Mass Effect won me over with (story, in game cutscenes, dialog, etc.)
I could go on but I really haven't played enough to write up a full on review, but I have played enough to know that the kudos and high scores this game is getting are well deserved. It does have some issues, like being the first of the series to make its debut in the multiplayer arena. While there are a host of options there, some of the interfaces are kind of clunky and I've been reading were the PSN/PS3 version in particular is having some connection issues (I haven't experienced ANY with the 360 so I'm even more impressed with multiplayer). But in the end it's just one HELL of a game and one that I hope I finish and know I'll continue playing online with friends for some time to come.