Excellent, amazing, fantastic. For about a month.
However, it missed something the previous GTA series had. After playing the story mode through, which features a mesmerizing story that will keep you immersed throughout, I just through it aside and got on with my life. It missed the playability we saw in San Andreas, the raw satisfaction you got from taking a break from the story mode and gallivanting around the streets. This may sound weird, but I missed some of the unrealism that featured in previous titles. Also, I wasn't thoroughly impressed with the cover system, it was laggy and frustrating when you were in a massively long mission and was killed when Niko took cover on the wrong side of a wall.
Don't get me wrong it was well worth the money and is one of the best games I have ever witnessed, but I am slightly disappointed that some of the fun is missing.