I played GTA Online (for PS3) last night and it was pretty bad honestly. Here's what happened:
Start out and make your character, go through a cut scene where Lamar brings you to a location and it forces you out of the car, and forces you over to a mission to start a race. I literally waited 10 minutes of it saying "Waiting for other players". It should have stopped every minute or two and said "Would you like to keep waiting"? The only option I had at that point was to hit the PS button and exit the game or turn off the system. There was no "going back" to the main GTA V at that point, or ending the "waiting for other players". Once it finally connected there were no other players, just me racing the NPC Lamar. It gives you 30 seconds or so to ready up and choose your bet/buy ammo, etc. So I waited 10 minutes and almost missed my chance to choose things before the race started.
The other thing I don't like is that you can set a car as your own (put a tracker on it and buy insurance), but you can't do it with the higher end "Premium" cars (basically the better cars in the game). It said I had to purchase them to unlock from the GTA Online store. I'm hoping you can also unlock them by your experience points from playing (that's how you unlock certain things like weapons). But I'm not positive and would not be happy if you had to spend more money on the game to use some of the better items in game.
My brother got online at this point and we got into a world together (seemed like it was only us most of the time, which was fine by me). And played for about an hour together. There were so many issues that we experienced:
Our mics only worked some of the time, didn't seem to have any rhyme or reason to why they would transmit sometimes but not others.
When he was driving and I was passenger, the car would freak out on the road. It looked like he was flipping and crashing into buildings and trees and all sorts of other things. It showed me taking damage (the red lights up the map), but didn't actually hurt me. The car was a complete mess however on my screen (but not on his). And if he got out and I went to drive it, the car was fucked up, but not for him. There were at least 2 or 3 times where he was driving and then all of a sudden he was gone and I was alone in the car. This also happened to him sometimes (both as passenger and driver).
There's really not a lot that interested me in the "jobs" either. Racing is really about the only thing that would. Death match, team death match, last team standing was actually kind of cool (one death only), except people camping the whole time (10 minute rounds). It will be nice if/when they implement the sports stuff like golf and darts and tennis. Also I',m hoping they have an actual casino, right now they have gambling, but only in the form of betting before a mission. I also heard you can unlock heists the more you play, which would be pretty fun as well.
It has some appeal value there, but not until they fix the horrible lag in game.
Thankfully I've put about 30 or 35 hours into the game and only am "60%" finished (haven't checked the main story progress lately, I'm probably about 75% of the way there). And I don't see the appeal of the single player game being lost any time soon. It's still the best single player game I've played.