I rated this a 6, and it's all for Jet Li's awesome (as always) action sequences. But even that modest rating might be too high considering the absolute awfulness of the script.
I cannot stress "awful" enough, here. From the so-cliche-it-hurts plot (dueling-crime-families, a la "Yojimbo" and "A Fistful of Dollars", melded with a tired cop-avenging-his-partner's-murder story), to the hamfisted dialogue, to the mindblowingly retarded "twist" ending, "War" is a magnificent failure.
But the action is solid, stylishly staged and photographed, and if you're a Jet Li or Stratham fan then "War" is still worth watching. Just go into this one with low expectations (even by action movie standards)... and perhaps switch the audio to Spanish or whatever for the last 15 minutes so you're not distracted by the ridiculous ending.