Online is Great! Buy it for that reason alone.
If you own PGR or PGR2 than the single player is what you have come to expect. Better graphics, better sound, more forgiving Kudo's system and repetitive circuits to achieve your next trophy.
Like I said, online is where it's at, as this is where the fun begins and before you know it it's two oclock in the morning and your still saying " JUST ONE MORE RACE"!
I've had it for about a week now and it's addictive to the point of asking myself if I should play it or not for the fear of being online for hours!
Buy this game.