This is my first GTA since I played barely an hour of GTA 3 and had fun with the flying tank exploit... (go forward, aim the barrel behind you and keep firing = flying tank). I'm more on the Saints Row side of things so this game annoyed me a lot during the first hour.
Couldn't start stuff with the cops.. die in one hit, tried to powerslide and every time the car spun completely around, the first missions were boring as hell and especially the fact that if you find any sweet jumps in a motorcycle sometimes it'll just kill you because you're too high or you didn't land *perfectly*. BUT after that and especially the online... it is quite fun.
Online - look for the missions Top Fun I, II and III and Extradition. Extremely fun missions.. jets with cannons and lock on missiles, although the helicopters are another thing. I can't pilot those to save my life.. they'll always keep swerving/rocking side-to-side whenever I pilot them. I'm MUCH MUCH better in jets then anything. It took a bit of getting used to that anyone in the same session can just roll up and kill you for no reason.
Here's a tip.. whenever you get money (however you get it) *IMMEDIATELY* open your phone and go to Internet -> Money and Services -> Maze Bank -> Deposit -> (click the button that says all the money you have) after that it's basically risk free; except for the medical bills which are pretty negligible.
It's also nice that you can put a tracker and insurance on your vehicle, that way if it ever gets "stolen" (Why would it? Just use the select menu and change Vehicle Access to No One or Crew + Friends and no random can get in it) or blown up/destroyed, just call Mors Mutal and pay $200 and your vehicle is back
tl;dr - Kind of annoying in the first bits and takes some getting used to but it is extremely fun, go buy it now