I was on Lulu, but I had a falling out with them when I asked them to ship me a book and it never arrived.
It would have been all-in-good, but they turned around and said I already signed for and received the book and I hadn't. What made me even angrier was the fact that their own tracking system showed they had never shipped it, the signature they provided me wasn't even the right name, and the tracking number they provided as proof was not mine - was not attached to my name and was not attacked to my account. Could they have messed this up any worse?
However, in all fairness, they did finally refund me, but I actually wanted the book and would have preferred they kept my payment and reshipped (yes, I was willing to test the waters again).
Now, before looking too deep into this, remember that this is an isolated experience and that I did have good experiences with Lulu in the past. I just think they are going through a rough period right now, and I do hope it all mends itself soon. :)