Sign up is free and they have a few games other than Settlers, by the way Settlers is called Xplorers here. Toulouse, which a Carcassonne clone, and two other games, Match and Roadblock. I haven't played any of these so I don't know what they are like.
You can play basic Settlers or Cities and Knights, ranked or unranked. If you play ranked your games get recorded and you get...well a ranking! You can opt to play against real players or bots to get a feel for the interface. I play basic almost all the time. One of the good things is that there are multiple maps to play on, not only the default island but many others created by the players themselves. My favourites at the moment are Fifth Element, Discovery and River Runs Through It.
As you can see from the pic, there are some white hexes, you don't know what resource these will produce until you build a road to them. Also the multicoloured hexes produce any resource, you choose when the number is rolled. This is the start of the game, the players have just placed there starting settlements. I am white (Coljen), I wanted to go on the multi at the bottom left but the other players tied that up!
You can play games to 10, 13 or 15 points, this is a 13 point game and is well developed now. I have got 2 cities on the multi and got a wood port as well. The other two players kept dropping the robber on the multi though.
As you can see there are still some undiscovered hexes and another multi was discovered middle left.
Here are a few stats of my play:
Dec - Played 20 Won 3 2nd 6 3rd 11
Jan - Played 3 Won 0 2nd 3 3rd 0
Feb - Played 66 Won 21 2nd 24 3rd 21
Mar - Played 63 Won 22 2nd 24 3rd 18
Fifth Element Games 51 Won 15 Lost 35
River Runs Games 35 Won 7 Lost 28
Forest Escape Games 29 Won 8 Lost 21
Discovery Games 21 Won 9 Lost 12
Christmas Games 14 Won 4 Lost 10
March of the Penguins Games 1 Won 1 Lost 0
Default Expansion Games 1 Won 1 Lost 0
Golden Circle Games 1 Won 1 Lost 0
Dutch Empire Games 1 Won 0 Lost 1
Default Island Games 1 Won 0 Lost 1
I didn't realise that I played that much!!! Anyway it's good fun and most of the players are friendly. I have met one or two that have a real problem if you drop the robber on them.....so I do it even more :) Give it a try you might like it.