I noticed on another blog that there is a lite version of the Exegesis :: BookPulse application that only includes the first few chapters of the Exegesis but appears to have all the other features. It is free and seems to me to be a good way to test the application out before you buy the full version. (Unfortunately, I don’t happen to own an iPad…)
The lite version is here: http://itunes.apple.com/us/app/the-exegesis-philip-k.-dick/id492161170.