Pretty good!
I like this game, you've got to really think about what you do at some points and just jumping around randomly will rarely get you anywhere.
However, after playing for a while, I find that when I lose a level more than twice, I'll quit the game and not come back for a few days.
Argument against the reviewer below me (mugin121) - it's clearly a chess-based game, if you're not into strategy then chances are you won't like it.
This is a very original game and I hope there's a Black Knight 2 coming up!