Both my novels started out with covers designed by me, then eventually got professional covers. I wrote about Turner's cover here, and CF2K's cover here.
The new Turner cover was uploaded to Lulu in October 2012 (c. 26 weeks ago)
The new CF2K cover was uploaded to Lulu in January 2013 (c. 15 weeks ago)
Guess what? Lulu still hasn't sent that data to Amazon, which still displays the old cover. So much for '6-8 weeks' - it is now half a year since Turner got a new cover!
Writers and readers both know how important a cover is for sales. It is vital. That's why I spent money on something beautiful for my books. But it is pointless if they don't show up on Amazon, and can't therefore tempt people to buy the book.
I contacted Lulu back in April. They told me that it only takes 4-6 weeks for the covers to appear on Amazon (i.e. fewer weeks than claimed elsewhere) and couldn't explain why it hadn't happened for me after 22 weeks. I followed it up on 8th April... 11th April... 24th April... 2nd May... 9th May... And no response from Lulu to any of my messages. They just ignored me, and the nice shiny book covers Lulu were given still don't show up on Amazon. Which is probably costing me sales.
At present I can't recommend Lulu, since you want a company that functions efficiently and acts when things go wrong, neither of which apply here. I'm considering moving to Lightning Source or Create Space. I'm sharing this so other writers can see the problem, and to try and get Lulu to respond. It's a ridiculous way of doing business when reputation is so important, but many companies nowadays just ignore problems until they are made public.
Update: 24th May 2013
After I wrote this blog post Lulu got on the case. As of today the new book covers show up. It's a shame you have to go public in order to get any action from some companies.