I really liked the theatrical release of First Class, but felt it ought to have been named "Magneto Begins". Theryaney's edit promised to trim the superfluous and redundant bits and turn it into an actual origin story. Sadly, I believe it fails in that.
As the-scribbling-man wrote, there are pacing issues throughout the film. The relationships between Moira, Raven, and Xavier are rushed and underdeveloped because too much has been cut. This, in turn, severely cripples the film, as certain scenes become jarring and almost incomprehensible. For example, cutting Xavier's recruitment to the CIA makes it difficult to understand the scene where he first meets Magneto. Additionally, moving Mystique and Xavier's first encounter to the end of the film takes away the basis for their relationship (and the transition was not done well - there's a noticeable drop in quality).
As a few others reviewers noted, the subtitles file is incomplete and some lines of dialogue are missing.
I really hope these issues are resolved, because this edit is very promising.