It is good. But it should be better.
SBK X feels like real riding. But since you use gamepad to control not your whole body (like real life). It is really difficult to control the bike in simulation mode. If you play onboard view, it is hard to tell whether the bike will spin. This is Not good for a simulation game. And the menu doesn't teach you how to ride well. If you have no idea about riding, the simulation mode will be even more difficult. The control of arcade mode is easy, but that is not bike.
Graphic:
Compare to racing games on PS3/XBOX, SBK X is just OK.
Sound:
Engine sound is good. Backfire sound feels like drum.
Game mode:
Enough game modes for both arcade and simulation. Career mode is good.
Bike tuning:
Lots of options for tuning. Great.
Only 5 different rider styles. I can't feel the difference.
Other:
No replay in Time Attack. Why?
Different bike has different performance. This is good. Different feeling when riding a v-twin, inline 3 or 4.
Since Milestone has much experience about racing game, SBKX should be better.