The quality of the layout and typography in commercially published e-books, that is. (So does the quality of non-commercially-published e-books, but those are beyond the scope of this post.)
To a large extent, the quality of an e-book depends upon whether the publisher is working from an electronic version of the manuscript as originally submitted (a lot of publishers these days ask for either electronic-only MSS or a combination of electronic and hardcopy), or whether they’re working from a scanned hardcopy version of the published book.
It used to be mostly pirates who worked from scanned hardcopy. These days, though, a number of legitimate publishers are working on bringing their backlist titles out as e-books, and a number of authors are doing the same thing with their own works for which the rights have reverted. In both cases, if the original book was produced during the typewriter era, or in the early days of word processing, scanning a sacrificed hardcopy may be the only way — short of re-keying the whole thing — to get an electronic text.
A lot also depends on whether or not the publisher bothers to have somebody proofread the e-book before it’s released. Dead-tree books are copyedited, and have the copyedited MS gone over by the author before being set into type, and then the typeset MS is gone over again by both the publishing house and the author before being sent to the printer. Even so, errors will creep in. Sometimes it’s just because no matter how many sets of eyes look at a thing, something’s going to get missed; other times, very bad stuff can happen at the printer’s end and not get noticed until angry book buyers start sending back their copies. Turning hardcopy into e-text, if the publisher is converting something that never had an electronic MS, often involves taking apart a physical copy of the book and scanning it page by page, which not only preserves any existing errors but opens the way for even more.
Some publishing houses clearly take care with the process of turning hardcopy into an e-book; others just as clearly don’t do much more than pour the however-generated e-text into a standard template and don’t bother much with it after that.
Your best bet is probably to write to the publisher about any errors you find. It’s not likely to get you a better version of that particular book, but it might encourage them to take more care with the process in the future.