After reading all the reviews about this movie being depressing or ponderous, I entered the theater expecting to be disappointed. Instead, I was pleasantly surprised to enjoy the mix of humor with action and horror. There were nice additions to the book material: for example, showing Hermione obliviating her parents' memories of her, with the melancholy that resulted from it.
The weakness is there, though, in splitting the book into two movies. The ending, if you are not familiar with the book, is confusing. And, although I greatly appreciated the Part 1 movie's inclusion of much of the book's detail, it would also be confusing for someone not familiar with HP7, in following the various secondary characters, like Yaksley.
I'll be back to see the movie, in regular projection: although I enjoyed the IMAX experience, I'm not sure it was worth the premium price.