Yeah, I'm almost certainly buying way more than I would have without the same day digital. Of course, a lot of these are going to be one and done affairs. I'm giving the books that I might have an interest in a shot. Some I'll keep reading, some I won't. My only gripe with the digital comics is that I really wish we were able to download the comics to keep on a hard drive. That way, I can still read my books even if my internet is down (which reading comic books has always been one of my primary "no internet" activities.)
I could be wrong, but I believe you do not have to be online in order to read the books with the iPad app.
EDIT: I just confirmed that you can read comics offline after you download them to the iPad.