I just got mine. I don't have a keyboard or pen yet.
So far I'm disappointed more apps don't make use of the larger screen. It just seems like everything is larger but not that there's actually more content on the screen. Since I'm not blind, that's a bit of a waste to lug such a large device around just to make things bigger. Hopefully that changes soon.
The speakers are awesome though!
There were a ton of updates when I checked iTunes tonight and, randomly clicking on them to see what the changes were, I noticed several said "updated for iPad Pro" or similar, so they're coming.