I like Radio Mirror Park, you guys have probably never heard of it.
I got 100% completion over the weekend, which isn't really 100% this time around for some reason. You only have to do half the stunt jumps, under the bridges, and knife flights, you don't have to do some of the Strangers and Freaks missions (such as the hidden Epsilon Program missions), and while you have to collect all the letter scraps and spaceship parts, you don't have to find all the underwater collectables. I went ahead and did everything anyway because I'm that sort of obsessive.
Having completed everything in single-player, I was going to try out the online yesterday but it was down. I think I might hold off on GTA:O for a few weeks until they sort out the problems and tweak the gameplay some more, because it sounds like a mess right now.