Are the special features as entertaining as the film?
It depends on which special features you’re talking about. There’s a series of documentaries called the Children of the Atom that is great. You’ll get several hours worth of material here going behind the scenes and covering every topic that you want to know about X-Men First Class.
X Marks the Spot makes you watch the film and jump to a special feature when you see an X appear on the screen. The videos that are attached to this special feature aren’t that worthwhile.
Cerebro Mutant Tracker allows you to search through the various mutants in the X-Men series and see pictures and video sequences with them in the X-Men films. I’m not sure who exactly is going to use this feature at all. It’s a nice idea but the information is widely known among X-Men fans and I don’t think non-die-hard fans will seek out this information.
In addition to these special features you also receive the Digital Copy of the film and 10 free X-Men Marvel Digital Comics.
Overall the X-Men First Class Bluray packs exactly the content that you want via its Children of the Atom series so I recommend picking it up.