A typical gaming session of GTA starts off with trying to find your next mission when you bump into a police car, "accidentally" run over the cop, and an hour and 5 stars later you are on the other side of town with a bazooka and you totally forgot what you were supposed to be doing. In this sense, Grand Theft Auto has not changed much at all since 1997.
This revelry is fun the first few times, but then you quickly tire of it and that's when most people stop playing. This time, for GTA 4, I decided to stick with the missions without wasting time goofing off in the Liberty City sandbox. I hoped the story and variety of objectives would hold my interest till the end.
Playing through GTA is like watching multiple seasons of a TV show. There is an overarching story, but most of the episodes (missions) are filler. The gist of it is you are an immigrant who was forced to flee his homeland. Here in America you hope to get revenge on the dude that caused all your problems. You go on a lot of missions and meet a lot of different characters, but most of them don't have any relevant impact on a storyline. Only a handful of missions advance the story, everything before that is basically just doing jobs for cash. Unfortunately, you are forced to do all the missions regardless. I would much rather have a shorter tighter story, with a lot of optional side-missions.
Overall, I'd say it was worth the play-through, barely. The game isn't that difficult, but there are a few frustrating missions where you have to repeat a bunch of crap if you die. Cabs are a life-saver, since they "teleport" you around the city so you don't have tediously drive everywhere. The mission objectives have a lot of variety, but there is a little too much stop-and-pop gameplay (much like Uncharted) for my taste. The level design usually has multiple ways to go about a mission, even if sometimes it feels like you are breaking the game (like instead of run-and-gunning through a warehouse full of baddies, you just drive around to the back).
Oh, and there is multiplayer too. Lots of different game modes, but the team-based stuff is the best if you can actually get competent players. Usually you end up in an SUV full of dudes who just want to drive around and blow stuff up. *sigh* Ultimately, the multiplayer is fun and very impressive technically, but quickly gets old (much like the rest of the game)
This game is basically Grand Theft Auto III perfected. GTA IV truly takes it to the next level, creating an almost 1:1 scale replica of the real world. The attention to detail is astounding. Almost every aspect of New York City is present (and parodied) here. Now when I walk around a real-life city, I think "wow, this is just like GTA". It's too bad they can't provide a compelling story without stuffing it with irrelevant side-missions.
So what's next? Well, if GTA V is just GTA IV with a different city, count me out. The GTA model might have life left in completly different scenarios (like Red Dead Redemption), but I think every drug-running gansta-killing scenario has been played out. The next logical step is... a GTA MMO. (or maybe a GTA FPS).