Some of it is refinement, some of it is evolution. I don't see any revolutions here, not for the iPad anyway.
The iWorks apps are refinement. Siri is evolution; with the addition of new databases and tricks she's, smarter. Maps is a step back so that Apple can go forward. They can't compete and win against Google if Google owns all the balls.
Hold in mind Apple has never been about revolution/change for the sake of itself. They have ideals, goals for their products. The closer they get to those goals the less radical each change will be. At some point it will be nothing but adding new obvious features and spit & polish. Eventually, as technology and culture allow, they may make another radical change to the phone market.
That's been their pattern for most other products. Something really new, REFINE, Refine, refine, then something new when it makes sense (or just a smidgen before it makes sense).
Until Apple has a solid reason to completely redesign iOS or the hardware, they won't. It will just get better, in a way that bores tech geeks but keeps people buying the product.
BTW, you can apparently create ringtones using Garage Band. Haven't checked it out yet, but sounds like hours of time killing fun.