As a general board games player (although not an expert in Reversi) I have some idea of the strategy involved, and I must say I like Muryan. The top two of the five levels are devastating, and even on Novice and Easy, although it is fairly clear how the playing program has been deliberately weakened, exploiting that is another matter. In one game it left a corner square open early (a bad idea), then fought for most of the rest of the game to prevent me landing a piece on it, which was impressive.
It is worth noting that, although there are five explicit levels, there are effectively ten levels in practice as switching off "Highlight Legal Moves" makes the game far more difficult - the dots pointing out legal moves tend to draw the eye to trouble.
Other than the engine ... good, clear 3D graphics and easy gameplay with scarcely a wasted click. A minor wording issue: "Lock Board Position" and "Reset Board Position" would be better as "Lock Board View" and "Reset Board View" as they are nothing to do with the position of the pieces on the board - they refer to the pan and tilt of the board on-screen.
The only enhancement I can think of is that would be nice to be able to save and load games as separate files (is there a standard Reversi notation, like PGN for chess games?)