I thought it was great. Certainly my favorite GTA (though that's not saying much, as I never cared for the series).
SA is the best GTA. V's missions made me want to rip my ears off: NPCs just don't shut the f*** up but I guess they gotta distract you somehow from the boring mission design.
I'm happy for those who found enjoyment in this game but this installment felt more like Grand Fetch Cutscene to me...
My two unsolicited cents.