[rbarooah]

As of iOS5, free and paid versions of apps (or any apps by the same developer) can share data, so the issue of losing data when upgrading has been solved.

There is also no reason the developer can't link to the paid version direct from the app - no heed for hunting.

I don't mind them charging in-app for features in principle. but I found that the free version wasn't enough for me to draw anything serious so it didn't really let me try out the app.

I think it would have been better to go with a fully featured free version with say, just one notebook with limited pages. That way users could use the app fully, and upgrade if they used it enough to need more capacity.