I wouldn't normally be this unhelpful, but: Yawn.

That's my full and in-depth review. If you do watch this movie you'll quite possibly do the same.

If you really, really, insist though... you do? Really? OK. My reasons are: unbelievable scenario (though setting very believable), characters it's hard to feel any empathy with, unnecessary lampooning of the Japanese, no particular plot development, no real story. I watched this at home and was hard pushed to keep going after the first 40 minutes of tedium. The occasional witty exchange (ish) does not make up for the fatal flaws.