I've published a couple of books with Lulu and I've been very satisfied.
The process of making sure the book format and paging and cover dimensions are OK are labourous if done on your own, but worth the effort. Their site contains more than enough technical information, though this might not be everyone's cup of tea.
The books were printed perfectly - and one of the books was a very special print, which required that the paging was backwards, something which was accommodated by Lulu flawlessly (whereas with Amazon's CreateSpace it was impossible to do it.)
Haven't had to deal with their customer service - everything I ordered arrived fine. The only minor thing was that, in three books (out of an order of 20) had the cover misaligned slightly, so the spine text was a bit off. But that is understandable, as the book was just on the threshold (just over 100 pages) of what is acceptable by lulu for text on the spine.