I have to say, the Casecrown cover is excellent. The Kobo fits perfectly, and all the buttons and ports are accessible with the cover in place (with the exception of the reset hole, but in theory that's something you should only rarely have to use). The extra thickness makes the home button a bit more recessed, but it's still easy enough to press.
The inside of the cover is lined with a fuzzy material that seems to grip the rubberized surface of the Kobo and keeps it securely in place, so there's no danger of it accidentally slipping out. In fact, it's held so securely that it takes a bit of pushing and pulling to remove the cover.
The magnetic clasp on the front holds tightly and is unlikely to pop open by itself, and the case is flexible enough that the front flap can be folded behind for easier one-handed holding. On the inside of the front flap are pockets for an ID and credit cards (or whatever) and two larger pockets that could hold a folded piece of paper. I told my wife that it's enough to hold everything you need for a night on the town and then realized how geeky that sounds when my definition of "a night on the town" is sitting by myself in a restaurant and reading a book.