Trance is a surprising movie that goes way beyond what the preview shows, and that's excellent for the viewer. It's a tangled web of reality.
The good. New developments at every turn. Tense story, and very imaginative. Good dialogs. Strong female character. The few seconds of hesitation at the very end are extremely well done.
The actors. James McAvoy, as the pawn turned amnesic, and Rosario Dawson, as the talented hypnotist, offer us each an incredibly good performance. And Vincent Cassel is surprisingly good, if still within his usual role.
The bad. The untangling of the story is not done very smoothly, unfortunately. The background story, when revealed, is told too quickly. It feels a bit pathetic. Sad, yes, but not as dramatic as it should be.
The ugly. I think that giving her a new lover was just unnecessary. The film would have been just fine if you cut that out of the end.
The result. See it, the story itself is worth the money.