Caveat: I was a beta-tester for this program. I offered advice to the developer about possible features.

Mac OSX chessplayers, if you've been looking for a program to help your analysis, to serve as a database for your games, or simply to use to play though master games from a book, this is the program for you.

Gambit allows easy manipulation of multiple variations. The integration with the crafty chess-engine is seamless and quick. You can open multiple PGN, adding and removing games easily. There's simple cut-and paste recognition of both PGN files and FEN notation. (Heck, Gambit is the best OSX PGN viewer on the market.)

Oh, yeah - you can also play against Crafty. Craft may not be the strongest engine on the planet, but unless you're a master-strength player, it's all you need.

If you want a game where you can play against multiple computer "personalities," and track your progress, you're probably better off with the latest version of Chessmaster. Gambit isn't, primarily, a program to play against (although it does that just fine.)

Gambit is, instead, a must-have for the serious player who would be using Chessbase products if they were on a PC. Compare the feature sets and price list (Chessbase is a $150 program, making Gambit a veritable bargain).

Gambit is significantly better than either Sigma Chess or ExaChess (both progams I grudgingly used for storage and analysis until I got Gambit.) The moment I got the first beta of Gambit, it became the only chess program I used.