This is maybe a bit premature, since I’ve only been playing with the program for a day, but here’s what I’m using so far.
I’m a PhD student so I have about 1500 PDFs in my devonthink database separated into about 50 or 60 different folders. Articles I’ve read are labeled blue, articles I haven’t are labeled red. This is a great set up for research, but reading articles on my screen isn’t that fun. With the iPad I can actually go outside!
Right now my primary way of using DTTG is to use it to find articles that I haven’t read yet, then open, read and highlight them in iAnnotate (though this is a bit confusing, see this thread). In theory I’d love to also be able to take notes in DTTG, but this might not be possible until iOS 4 comes out for the iPad and integrates fast app switching.