Crazystone is one of the new, strong go playing bots, along with Zen. When it plays on KGS, it is 4-5d.
I bought a copy of it the other day for 60$ US. Although the algo was designed by a french guy, it looks like the UI was done by a Japanese company and then overlaid on top of the algo.
Unfortunately it is not that good. Very low end. There's crappy music, weird icons showing crazystone's opinion of the game state. The button design is pretty horrible, and there's barely any configuration available.
There's no way to easily replay a game and get Crazystone's opinion on the moves
If crazystone is thinking, but the focus is on another window, the UI will not show crazy's move until you click the window to set focus again! This is just shockingly bad, and extremely annoying as well. It basically means that using crazystone on long time settings will be impossible, because if you want to do something else while it's thinking, you will have to keep refocusing the window.
You should be able to see crazystone's thinking, live, in a little window off to the side - the moves it's thinking, the predicted scores of each choice, how many variations it has considered so far, etc.
Mousing over each move in that list should highlight that point on the board.
This should work for both player's situations - not just Crazystone's.
And there should be an option to "force" the move based on the current best choice, or to force crazystone to play any of the sub-moves.
The longer you left it running, the better the evaluation would be.
With this, you would be able to simply replay one of your own games, and analyze it as you go
There should be a command line client ot crazystone so you could send it the current version of a game, with various options for how long it would think, and it would return information about it's thoughts on the best move.
With the command line it'd be pretty easy to set it up to evaluate games, and annotate them with the biggest 1 or 2 "mistakes" - the played moves which were worse by the biggest differential from the options available.
Crazystone is awesome, but this implementation really sucks.