They offer a very wide selection of markets and they also have options/props for a lot of sports. I would have liked to see more PvP props for basketball, but no such luck.
Their target audience is scandinavians, and as such they will limit (or so I have heard) you if you beat them badly on NFL/NBA/NHL and whatnot. As far as I can tell I have never hit any limits, but I have't placed any big bets on anything else than soccer.
In my records I see that they have always paid me within 24 hours to moneybookers and neteller. If they even take US players I am not sure how convenient it would be to deposit there as they don't seem to offer **/** and some of those options.
The customer service there is really fast, and I think they have a guarantee on the site that says you should get a reply within 20 or 30 minutes, if not you will get compensated.. at least they used to have this in the past.
The only gripe I would have with these guys is that they are in Malta. But they have been around for years and they have always been solid, so no reason to worry too much.
If you want to compare them to any book out there it would have to be
NordicBet.