It seems that my Othello game is doing well in the market, which hit 768 downloads so far, and ranking in 98 worldwide in all free games. (Just a small comment for Microsoft, it’s better to include search for ranking. 
) But the problem is that there is no one leaving comment for me to improve. Anyway, I will find time to update it to become better.
Some Screenshots to share:
I think you need better graphics and a better user interface. And why don’t you make it as a fullscreen game? I don’t see any point having Windows phone 7 interface on top of your game. Anyway, you can see comments on your app on this site.