Let's think about this for a second. Yes, it is still possible to issue a technical review of the movie, commenting on things like camera angles and sound editing, but my understanding is that this is still largely the same technical team that has been responsible for several of the other movies. Similarly, the director and writing team have already had a chance to express their views on a variety of themes and motifs in the Harry Potter universe. I think it would be a reasonable to assume that their work here will continue what they have already established elsewhere. Thus, every viewer of the past movies has the necessary experience to determine whether, based on the earlier movies, they want to see the new one.
Further, it is common practice for some to comment on the degree of faithfulness of the movie to books, or the creativity in the adapting or the sequencing of different parts for a movie audience, but the whole film-in-two-parts aspect of The Deathly Hallows suggest that we can only really evaluate Part One in the context of how well it works in conjunction with Part Two.
Finally, while there is a legitimate review to be written for the small segment of population who have not read the books nor viewed any of the movies but (for some strange reason) decided that Episode 7 of 8 is where they want to be introduced to the world of JK Rowling, those few people are in need of a review written expressly from the viewpoint, for that purpose. I would suggest that few of the writers reviewing The Deathly Hallows are capable of such a feat.
For most of us, if we have watched the previous movies, or read the books, then we have already either made a heavy emotional investment in the movies, or else dismissed them long ago. No rewiewer can adequately express the degree to which The Deathly Hallows will live up to our own expectations.
