There's a bunch of reviews in the unpublished queue here that have never been pushed live for a number of reasons - many of them boring admin problems, some of them because the book hasn't exactly been to this reviewers taste and, believe it or not, I don't always like posting negative reviews, especially if I've struggled to find a positive about the book. I'd hasten to add - these are in the minority / most of them are because I've been flat out and haven't had a chance to verify / check the review content.
Still, after a bit of pressure in the background, I'll start pushing some stalled reviews out - some of these may be in very shortened format / comments only with apologies for the brevity, but they are probably the books that I've really struggled with.