I suggest renting it and beating the Single Player mode and then Returning it. The multiplayer is really nothing special, unless you are into the free-roam mode because that is the only mode people really play. The other Online game Modes are rarely played and its hard to get a game started because people leave so often.
Its not even a game I would recommend buying. The only games worth buying are games that you wouldn't mind playing again, and this is not one of them. Once you beat it, your done.
Multi-Player = Not Worth It. ( Unless you like the Free-Roam Mode )
Single Player = Definitely Worth It.
To be honest this game gets old fast. After the initial awe of the gorgeous LA visuals and first few missions you get the gist of what you will be doing the rest of the game. Go here, kill person A, grab loot, leave. You can obviously jack around and just kill cops and create general mayhem but it gets old fast...iit might have been fun when San Andreas came out but this is 2k13.
That's where the online comes in. If im going to be running around shooting at stuff it might as well be at other players and with friends. The one thing I will say is the apartment/vehicle element to online is the ONLY saving grace. I legitimately enjoyed collecting vehicles and customizing them (partially because I used the LSC glitch and had enough to buy the Adder, etc.).
unfortunately online is ridiculously boring when it comes to gameplay, missions, and racing. You know...the actual GAME. You can only run around and gun so many people down and go so many repetitive online missions which involve monotonous tasks like drive here, collect loot, kill ambush. The missions now don't pay all that well considering how boring they are.
Overall this game is pretty overrated. Has great graphics but the gameplay and online mode are supremely boring.