On this evidence, the design of the hardbacks has been tweaked to bring them more into line with the softbacks (same fonts etc). They've also got the same matt finish, with some lovely spot varnishing which looks fucking sweet. As we've come to expect, the design and presentation all round is awesome, putting to shame just about any comic book publisher I can think of. There's also loads of extras which help to bulk it out, and give better value for money. Can't comment on the story itself as I haven't read it yet (saving it for after Case Files 5).
I used to be a bit reluctant to buy the hardbacks - they are still a bit pricey, and they seem a little impractical (Red Seas, Lobster Random) next to the softbacks. But this one at least, makes sense to me - a deluxe edition of a one-off story.