Well. Could have been a LOT worse.
It was actually not bad. Although that was after half a bottle of wine and a curry, and I had a strong desire for brandy (or similar) once the film had finished. Not sure if that was the film's fault, though.
Not bad. Although it didn't really 'get going' - it started mid-paced, continued mid-paced, and ended a little abruptly, really. If it had contained a bit more substance, I would have said that the ending was deliberate so as to leave a second film viable - however, I don't think thats particularly likely.
In short - if it is on TV, or you are offered it as a lend - it's worth watching when nothing else is available. You won't rue wasting 2-3 hours of your life, as with some other films (Golden Compass - pfah). Do not part with money on the behalf of Jumper, though - that you would regret.