Neeson creates a likable, sympathetic character. This is necessary for the heightening of tension, which screws on inexorably until you just don't see any way out for him.
The camera-work was particularly masterful - creative, meticulous, thought out to a granular level. There are two particular action-pieces towards the climax that are breathtaking, at least one of which looks like (but surely isn't) a single, extended take. The camera defines space and gravity, and is part of the expeience.
Yes, there are some credibility straining factors. But it is after all a movie, not a procedural. On the other hand, there are some very neat surprises.
Glad we saw it!
