First of all, thanks for the pdf supporting on wp7. Altough i use adobe reader on wp7, there some issues that make the experience sometimes frustating.
There's no go to page or slider page as on Android. This make the experience incredible frustating or just almost to impossible to read a book like 1000 pages.
Secondly the rendering of pages its a bit slow compared with other mobile versions as the startup time. I mean really slow...
Are you planning to release a new version soon? If so when?