I have been using Chessmaster since version 6000. I have 9000 which I enjoy but haven't used it since going to Leopard.
It has some good tutorials on it (carried over from 6000) and the graphics are pretty. It's opening book is excellent.
The way I use it is I take a game I have played against a human opponent, either online or in a torny, enter the game into the computer. Then go the spot where the game started turning south for me, and then get the computer to come up with some moves.
Often it highlights a good combination I missed.
However, its always been a tad flakey at times. When it analyses moves ahead (and speaks it out to you) some of them seem poor and silly choices.
And the developers seem to ignore the problems. I wonder if it's ever going to get bug fixed or majorly overhauled.
There is a real opening, imho, for great mac chess software. Chessmaster 9000 is merely 'good'.