Actually I might just have to say "Flashback" is even worse than "X Men: First Class" but its a close call.
I'd actually say the other way around. My brother gave me X-Men: First Class for Christmas, and having never seen it before I thought it was going to be great because most of the critics loved it. Well, suffice it to say I didn't love it, or even really like it for that matter. It was just okay. It had its good moments, but on the whole it wasn't very satisfying. Flashback was at least entertaining.
Anyway, sorry to go off on an X-Men tangent.