The handling was less accurate than in Vice City. Maybe they did it on purpose, but it makes the game less fun.

I tried different cameras, but I didn't find one that I like. The distance between the camera and the car isn't constant, which is annoying, and sometimes it get too close (when the car is stopped or driving slowly) and I can't see a thing.

After the masterpiece that was San Andreas, teh expectations were just set to high. It also doesn't help that gta4 was literally 1/2 the game san andreas was. The mechanics work great but it was just missing a lot of what was in SA. Clothing variety, bodybuilding, melee variety, JETS, mini games- demolition derby etc.

^ This.

Sure the controls are a bit "stiff", but imo, it definetly made the game more realistic and in my perspective, it made it easier to drift in GTA IV rather than Saints Row. Not saying Saints Row controls were bad, just that the GTA IV controls appealed to me more. Saints Row's controls seemed too easy, not that its a bad thing, but i prefer GTA IV's.

The story is a bit slow/boring at times compared to other GTA's though, I can agree with that. But imho, I like the game. I didn't feel the need to cheat at all really. I don't know what all the fuss is about :P.

P.S. I've played GTA IV on the PC and the gameplay (reffering to lag) was no problem at all for me. Idk if it's just because i have a nice PC or what but I experienced no lag whatsoever whenever i played GTA IV on my PC.

These 3 were my biggest problems with it also.  Like other people have mentioned, I found it a step backwards from San Andreas as a game.

I felt like it took a step back in terms of exploration in the series, planes, trains, monster trucks car mods, loved the out door exploration on gta san andreas, you could literally explore tons in that game, gta4 seemed kinda restricted (maybe they were just testing the water on new consoles)

It was TOO realistic to be enjoyable. I liked being able to run around and get hit by cars and jump of cliffs in GTA: SA, and then be able to get back up again after 2 seconds... I'm still looking forward to GTA V though.

it was inferior to San Andreas, a lot less things to do

for me it was everything that i didn't want tbh. it became more realistic and compared to San there just wasn't that feeling of jokes etc. (double dildo, Planes, Quads)
i loved the online though

Oh yeah, and you couldn't drive planes either.

The freaking mobile... CALLING ALL THE TIME!!!