They did a damn good job with it. Not perfect but damn good. Best movie I've seen so far this year (which I realize isn't saying much since most of the films this year has sucked so far).
Loki had some good depth of character to him instead of being just "Mwahahaha I'm so Evil."
and of course after the credits we get another hint at things to come.
Marvel really knows how to get their properties right on the big screen, looking forward to Captain America now more than ever.