I agree with most of what Ebert said in his review.
I am very impressed that Joe Wright, who is known for Pride and Prejudice and Atonement, was able to pull this off so well. This movie had a cool look to it, a pretty cool premise and a surprising amount of depth.
Hanna was an engaging character. I really enjoyed her run-in with ordinary folks on vacation, as it really allowed us to understand how different she is and gives more weight to her situation.
This movie easily could have been a one-note revenge picture with a cool, young assasin in the title role, but there was more to it. Great acting, pretty good pacing (although it started to drag in the last third) and the soundtrack really helped to push the tone.