I've been looking to replace an old Saitek Kasparov chess computer for a while, but didn't want to spend several hundred dollars to do so. After taking some time to my due diligence I decided to pull the trigger on the M810 (ChessGenius), with the Chess House return policy as my 'get out of jail free' card just in case the unit sucks.
It doesn't suck.
To start off, the game itself is compact enough to fit in a courier bag, briefcase, backpack, or computer bag but still large enough to qualify as an adequate playing size and easy to see board layout, with 23cm squares (just about 15/16 inch).
The game play is very good, and the computer is difficult even at the lowest level (Fun 1), with multiple play options including customized board positions. Starting and moving around through all the options has a little bit of a steep learning curve at fist, as the controls and UI are a little difficult to pickup, but once one figures out the navigation logic it becomes easy to move through the various options (play level, sound, etc). If needed the computer will offer hints, as well as allow one to 'see' its thinking process during moves. There is also a game analysis option, but while helpful at times, it isn't fully robust. And the engine powering the computer is ELO rated to 2000, so this game will suit anyone from beginner to IM level.
Others have mentioned problems in the board sensor recognizing pressure. I haven't noticed that, though I did find that pressing on a square with the flat bottom of a piece is more troublesome than using the edge of the piece -- and in fact the instructions do say to tilt a piece and press the square with the edge, rather than just press the piece flat on the square. There's a reason the instruction say that.
There are a couple of issues that prevent a five star rating. The first is the fact that the game is a little flimsy in construction, with the plastic being a bit thinner than I expected. Secondly, the magnets used on the pieces are very weak, failing to hold the piece in place even when the board is tilted or jostled only slightly. This is made worse by the fact that the pieces themselves are extremely light. So, playing this on your lap or where there may be accidental bumps is not advised. Using denser/heavier plastic for the pieces and/or stronger/heavier magnets on the pieces would have been a great idea. And lastly, as so many others have said, the storage space provided is completely inadequate for the pieces. One needs to tetris them into the compartment, but even that is no guarantee.
But none of that impedes gameplay (well, maybe the problem with the piece weight/magnets). All in all this is a very strong unit for just over $100