They have five faction boxes released at the moment- Sting of Lolth (spiders), Heart of Cormyr (the only good guys, haha), Tyranny of Goblins, Curse of Undeath, and Blood of Gruumsh (Orcs!). It's a nice mix of baddies. More factions are planned, but I haven't heard anything beyond that.
We have three of the five boxes- Cormyr, Undeath, and Goblins. There are rules to break up a single box into a two player game, but honestly, it's way more fun to just get two boxes. You can also play with 3 or 4 players, but I haven't tried that yet. We'll probably pick up the Orc set at some point in the future.
What I like most about the game, other than it being self-contained, is that it's quick to pick up but not so simple that you get bored with it quickly. It's a little different than most skirmish games I've been playing lately, as it's card-based in a way not too dissimilar from MTG. The board is marked with a grid, and each creature gets to move so many spaces per turn. Games take about an hour.
The pre-paints are pretty nice and the sculpts of the figures are good. As much as I like painting, it's refreshing to occasionally play a game where you don't have to paint the minis yourself :-)
The trailer for it kind of fun, too. I'll just leave that right here...
Happy gaming!