Overall, I thought the concept was generally good, with weak execution at points.
As for Han's death scene, it's quite plausible that the plot was constrained by the number of movies Ford was willing to sign on for, and the fact that he had apparently wanted Han to have a death scene in RotJ. It was well executed, and didn't entirely come out of left field either (as often happens when a key character in a series is killed off for teh dramaz).
I was rather disappointed by what they did with the TIE fighters (for what they needed for Poe (sp?) and Finn's escape scene, I would have rehashed the visual looks of the TIE bomber, like they did with the X-Wings, and used that for the escape). I also would have liked to see a bit more of a force mixture among the TIEs in the battle scenes.
I didn't mind the degree to which the plot ran similarly to Episode IV (it did differ at key points, notably Ren as an explicitly wannabe Vader), though I do agree with those who say that Death Star round 3 was a weak point. However if I had been advising Lucas on Episode IV, with the certainty that the story would span 9 movies and a bunch of tie-in books, games, etc. (instead of just the one that was all Lucas knew he'd doing before the box office results came back from IV), I would have advised him that the first Death Star was a mistake for a series of that scale, because it leaves the question "why don't they build another" with no great answer. Of course, then Episode IV would have been a vastly different movie, even if the flavor was largely the same.
To finish, I'd say that what most impressed me about the movie was that it actually made the whole "Solo kid turns to the dark side" bit work. If you had told me a year ago that they would use, and in so doing basically canonicalize, any element of the post-New-Jedi-Order expanded universe as a key plot element, and that that would not ruin the film, I wouldn't have believed you. NJO was where my headcannon took leave of the Expanded Universe, and I never would have thought any part of it could have been made to actually work.