Assassins that hijack people's body to commit their murders. Interesting concept, though not revolutionary.

The main character is well portrayed, specially the dissociation that comes from her work, the way she trains when inside a new body, the way she tries to become herself again when back to her own. That's the most interesting aspect of the movie. Following the mission itself, while in the Colin's body is mildly interesting.

The killings are uselessly violent, I guess it serves as a tell sign that something is wrong with her, as she was supposed to do it cleanly and fast, but this aspect is never really developed.

The second part, inside Collin's body [spoiler]after she fails to come back to her own[/spoiler] is less interesting. The I guess the conflict between [spoiler]the two spirits in one body[/spoiler] is the whole point, but it does not really take.

Small role for Sean Bean ([spoiler]he dies[/spoiler]), he's good (obviously). Jennifer Jason Leigh has less of a chance to shine.

Bonus points for [spoiler]taking over the child's body at the end[/spoiler], that's a good idea, however, as we've seen how the technology works, it seems like it would have been unrealistic to do. It seems like a last minute measure and/or a precaution, but that's not how it works. [spoiler]They can kidnap him long enough without the father noticing ? She would also have needed a long adaptation, specially with such a different body. Also it seems it must always end with the host's death, so what was exactly the plan here if it actually went well ? Get her back, and sorry we had to kill your child just to be safe ?[/spoiler]

This whole things is basically an episode of The Outer Limits.