Probably the most significant iOS release since iOS 1.0, primarily because it seems the world is flat after all! No more skeuomorphism which, in my humble opinion, is a huge move in the right direction.
Anyway, I'll leave the specific feature details to the interweb, but the point I want to make here is please please think once, think twice before diving into iOS 7.0. Tempting as it is, very very tempting, at least upgrade your non-primary device first, perhaps that old iPad in the corner of the room. Try it out, kick the tires and test your critical apps, then test some more. Hey, even try making a call, send a text or write an email and if you're happy, and only then, take the plunge and upgrade you main device. (Assuming of course you've backed it up ahead of time!)
Good luck and welcome to the world of flat simplicity! Where have you been all my life.. well, since June 2007!
Great articles from OSXDaily, iMore and iDownloadBlog which sum up the risks for early upgraders!
A location for inspiration and comment... (but primarily just my point of view)