Good game
First, let's talk about the overall gameplay itself. It's a huge step up from GTA:SA. The physics in this game are amazing. The cars handle very well, but it definitely takes some time getting used to it. The "ragdoll" physics implemented in GTA IV are very interesting. For example, say you get hit by a car that's traveling at a fairly high speed; Instead of just bouncing off and hitting the ground, you'll be sent flying through the air, and you may even flip across the ground. The same physics apply to not just Niko, but to all the pedestrians as well. Trust me, it's extremely funny to hit a group of pedestrians at top speed and watch them all go flying across the pavement.
The weapons in this game handle much better than in previous installments. Not only do the weapons not sound similar, but the way each weapon handles is much better than previous games. If you've played a GTA game before, chances are, you've most likely been in an all out gun battle. Never has it been for fun than in GTA IV. A big reason for the success of this is the newly added cover system. While it has its flaws and while it's by no means perfect, the cover system allows you to take cover anywhere. If you need to press against a wall if you're pinned down by fire, simply activate the cover system by pressing R1. (default controls) You can also take cover behind cars, low walls; almost anything! While not perfect, the cover system is by far, one of the best additions to the latest GTA.
Next, the graphics. GTA has never been known for its graphics. GTA IV is no different. It's one of the weakest areas of the game, but the graphics do not have to be good to make a game fun. It's actually not a big deal at all, and you'll probably be somewhat impressed when you 1st play the game.
Next, probably the biggest letdown of the entire game. The framerate! While no one was expecting R* to offer up a game with the framerate of a CoD4, for example (60 FPS), GTA IV totally lets the player down in this department. There are way too many hiccups and glitches in the framerate, and it's almost unbearable when there's a lot of action on-screen. While the game runs fairly smooth most of the time, the action really slows down due to the poor framerate.
The sound effects and overall sound in GTA IV are very good. For an entire city that would offer up so many different sounds, you really get a feel for each different thing. For example, if a car passes, you can hear the bass from the radio playing in the car. The way each individual car sounds is distinct to that particular vehicle, and as a result, it enhances the overall experience while driving.
Next, the story. GTA IV's story is the best by far in the GTA series. Offering up close to 100 missions. (including side missions) I won't give any details about the story, but I will say that the story is very immersive and will keep occupied for at least 50-60 hours. (assuming you don't do just the missions)
Online play in GTA IV is very fun. While I am unable to play as much as I'd like due to sorry internet service, what little I have played, the online portion is very fun. Multiplayer is accessed through the in game cell phone that Niko carries. Scroll to multiplayer, click, and from there, you're able to choose from various game modes. The great thing about GTA IV's online is that you are not limited to a small area or map. You can play in the same Liberty City you play in during the single player. You have the option of playing in a specific part of the city, but you can play, without being limited to a certain area as well.
Overall, GTA IV is a fun game with some minor bugs, but nothing too serious. The only really bothersome flaw, in my opinion, is the framerate. Graphics aren't great either, but that's no big deal. The bottomline is GTA IV is a great game, with a good story and tremendous replay value. You can spend hours on end exploring Liberty City to try and see all it has to offer. Trust me, you will enjoy this game!