I'm actually enjoying B-spec quite alot :-) - It's lovely to watch a race once in a while (one you havent raced - I don't watch replays so much as I know what happend, but they are awesome imo!). Its like watching motor sport in TV, and instead of yelling at your favourite driver to push faster, you actually tell him to :-).
I try to take a car very close to the AI to get a awesome close race, making my decision very crucial - means I have to give me orders almost every time the cooldown ends. Enjoy those races.
There is a few AI bugs, like when driving on a long straight and your relavtivly far from the car infront, your driving tent to slow too much down, instead of drafting a bit, and drive out - he does that even if far from the next corner. But its not always, not sure what does it.
I'm not so happy about the UI - would like to have a pitspot counter, a pitstop indicator that shows when drivers are pitting, and would like to see the fuel and tire wear while in live timing screen. Also think there should be more information of best sector time, and who is gaining on you, like in GT4. Also found a bug in live timing screen, for tracks with 4 sectors - the 4th doesn't show.
But overall, I love it!