GTA4 wasn't a terrible game, it just lacked a whole lot of content, but it also did not deserve the 10/10 it got from every review.
I think the problem was that there were no rewards for anything you did, meaning that there was less to do/dick around with after you finished the main story. I mean in earlier GTA's as you were finishing up the main story you could buy properties and do missions for them and once you finished them they rewarded you in some way be it either with a regular cash income or stuff like the Jetpack for finishing one of the airstrip missions etc
Same with the hidden packages, when you found all 100 and you got all sorts of goodies delivered to your hideouts, where as in GTA4 you have to kill 200 pigeons, thats right KILL with no form of silenced weapons in the game meaning that everytime someone is close by you have to leg it from the cops =/ And all you got was some **** helicopter that couldn't kill ****.
Also one thing I hate Rockstar for leaving out is the car modifications that you could do in SA, it would have been fantastic in GTA4
Edit: Forgot to mention that the weapon variety was also severely lacking too.
I think the problem was that there were no rewards for anything you did, meaning that there was less to do/dick around with after you finished the main story. I mean in earlier GTA's as you were finishing up the main story you could buy properties and do missions for them and once you finished them they rewarded you in some way be it either with a regular cash income or stuff like the Jetpack for finishing one of the airstrip missions etc
Same with the hidden packages, when you found all 100 and you got all sorts of goodies delivered to your hideouts, where as in GTA4 you have to kill 200 pigeons, thats right KILL with no form of silenced weapons in the game meaning that everytime someone is close by you have to leg it from the cops =/ And all you got was some **** helicopter that couldn't kill ****.
Also one thing I hate Rockstar for leaving out is the car modifications that you could do in SA, it would have been fantastic in GTA4

Edit: Forgot to mention that the weapon variety was also severely lacking too.