From what I've read, the events that happen in Bourne Legacy succeed the events from the Bourne Ultimatum. They are just using another character (Aaron Cross) with familiar characters (like Joan Allen from the first 3 movies) from the Bourne series universe. While Legacy is considered a spin-off to the original Bourne films (with Jason Bourne), the storyline follows in continuation. So it's not just another spy/thriller movie. Important.
I saw this film this weekend, and I did not miss Matt Damon one bit. Jeremy Renner did a fine job. Enjoyable flick.
I really thought this one was lacking in a big way. It was average, at best. Did a poor job developing Renner's character, especailly for how long the movie was.
I thought the ending was abrupt. Then I realized the movie was over two hours and I thought, "how did that happen!" movie moved pretty quick and I thought it covered a lot of material.
Users a critics seem to agree to an average of 6-7 out of ten. I'd rank it a little higher. Thought it definitely kept me entertained, had an interesting spin off story line and was extremely well acted, though I guess that should t be a surprise. The story could have been a little tighter, there was a little too much over-explaining, and the ending was abrupt. It was a little lite on action, though not a ton. Just some of the action scenes left some potential on the table ... Like the factory in mamilla ... Lots of opportunity there. Also the ending chase beginning with the roof sequence was way too much of a copy-cat. But a very entertaining movie. Still much better than 99% of the crap that's out there.