One of the other major things with picking up any new library or engine is documentation. Some of the developers of these like to hope that all you need to know is the list of functions, but sadly this is not so. If there is insufficient documentation, it's not a very good starter library, let alone an easy library to get to know how to use it well.

First and foremost a game library or game engine will live and die by it's documentation.Especially all those that are supposed to be all-encompassing. I'd have to warn away from libraries and engines that don't have proper documentation, especially for someone new.