>>I was a beta tester for them, and there were a couple of things i didn't like about it.
The main one was the fact that you had to also download their viewer to use the ebook...<<
True, but it does give some more functionality than pdf and, if you don't have reader installed, you have to download a viewer to read a pdf also. I've been suprised by the number of people who don't have reader installed. Plus, you can bundle the viewer with the book so it's only one download (altho the reader will require an install).
>>The second was that it was a bit difficult to use...<<
I found it extremely easy to use - both to read and to create in. Perhaps there have been some "user friendly changes"