Have been into car racing games for many years now with the occasional dip into biking but always jumping back out again due to the lack of anything good. Rented SBK from a local store, set it straight to simulation mode (as I always do) - this is my experience:
Gameplay (5/5): very, very difficult to handle (which so many games fail to achieve), so to finally start laying down some respectable times after a few hours felt extremely worthwhile. I always use in-car or hemlet cam views for realism - certainly achieves this in this game. The back wheel snakes around both on cornering AND braking (again, something most racing game developers don't manage to realistically achieve) with the option for mutual breaking or separate front and back. All in all, a thrilling experience.
Graphics(3/5): could be better I feel (MotoGP 4 looks much better). That said, revert to Gameplay above and you won't notice much. Wet weather graphics look much better than dry. BIGGEST GRIPE: why does it take 40 seconds to load a track and another 40s to load the menu afterwards? This becomes extremely tedious..had it not been for this fault, I would have purchased the game? GT4 has an 11 mile track which takes about 10s to load!!
Sound (5/5): simply excellent, high whines through to deep and dirty roars.
AI (3/5): can be annoying when someone hits you and only you fly off your bike. Same goes for if you hit someone and again you seem to be the only one in the gravel.
General: good number of tracks (22, don't know if more become available) incl. Brands Hatch, Magny Cours, Silverstone Int'l (not GP), Brno and Valencia.
As said, excellent and thrilling game hugely let down by tedious loading times.