Please don't misinterpret my post as a recommendation. 
For me Windows 8, 8.1 is essentially unusable without a touch screen, and even then a far cry from Win 7. The only thing which helps is an extension which brings back a good bit of the usability of Win 7 and still works in Win 8.1. There's supposed to be a way to get Win 8.1 to boot directly to the desktop as Classic Shell allows, but, consistent with the rest of Windows 8, I was unable to discover the secret word necessary to do that. The big advantage of the .iso file is a fresh install; yesterday's initial 8.1 Preview was an upgrade to an existing Win 8 installation, plus a long agreement that seemed to have a variety of provisos about software you installed that would stop working when the Preview did.
While Mavericks seems to have a lot of improvements under the hood, my major concern has been that my current software can run in it with no difficulty. I think I can breath easy.