2 of the 3 games are fun and easy to play, but getting money is another story.
I myself am not a big gambler so I don't know any of the games these games are based off of. Keystone is a dice game that has you bet on a roll of 3 dice. This takes some gambling skill, but not to much. The best of the games is Fortune's tower. This is a blackjack-type game that is fun, addictive and even takes some skill. The last game is like a slot machine, and it is about as boring as, well, a real slot machine.
Like I said earlier, you get 500 gold to play these games with. Like real gambling, there's a big chance of losing it all. But if you have some skill and some luck, you could also earn money.
This game is not really worth playing unless you are going to get Fable 2 because if you win money here, you can transfer all of to (and unlockables you earn, along with your debt) you Fable 2 game when it comes out.
Nevertheless, this is a solid Xbox live arcade title, if only there was a game that took some skill like in the original Fable, along with these titles. If you want to get and you want to get Fable 2, just pre-order the game.