--I wish the only problems were just with formatting with some books, the ocr errors with complete words changed from the print edition (an example I can think of is "full" moon to "fun" moon) upset me the most. If I don't have a paper copy to compare to, I just sit and wonder at times if something might be wrong and I can't just go and check it. Also, lack of proofreading, obvious grammar errors, (not to mention just plain bad writing) etc., etc. These problems are rampant, I'm frustrated and I've only been reading ebooks for about 3 months (other than the occasional pdf on my computer before that). But, I've decided the benefits outweigh the negatives, though I wish the same standards applied to paper editions were applied to ebook versions (maybe in the future?).
--I guess everyone will just have to decide what they will or won't tolerate in any particular ebook, or if they're willing to change or convert it if necessary.