As with others, I find that there isn't a huge difference between browsing online and browsing in a store. There are two notable exceptions: used book stores are more fun to browse than the online bookstores because they have many titles that didn't make the transition to digital, along with more varied selection (rather than being dominated by the latest releases). The second reason is that flipping through a book in a store gives me more information than downloading a preview, especially for non-fiction titles.

As for why I made the jump: I've spent a couple of years living in communities where books are few and far in between. It would be possible to do mail-order, but ebooks offer more conveniences (ability to review part of a book, ability to access it instantly, easier to transport when travelling/moving).