If you're reading this, you've most likely been playing through the LEGO Marvel Super Heroes game, and have pretty much enjoyed it. I certainly did!
What you get here is essentially a skin pack at first. The highlight of this are, of course, Dark Phoenix, who in-game is Iron Man and Jean Grey combined. Those of you who know the comics will be happy to know she's one of the most powerful in game characters. The runners-up are the fan favourite Winter Soldier, Falcon, and the awesome purple-comics Hawkeye, who goes really well with the Cloud Rider vehicle.
The bigfigs are Thanos, the Mad Titan, with the added feature of shooting stuff, and A-bomb.
The rest are fairly simple - Beta-Ray Bill as Thor, and the Venom/Spider-Man suit.
Another feature is the in-game races, which you can only use with the Spider-Mobile and Hawkeye's Skycycle. They really are a gripe when you have to go all the way back through the game to get the vehicles, as only they can work.
In all, lots of fun. A bit more for the fans, as some particularly comic-centric characters are included, but worth it, preferably on sale.