As far as the keys, yes they are certainly playable, but only up to a point. Fine for single note at a time melodies & runs, but definitely not for attempting much beyond that like pianistic style Shearing block chord melodies. That said, I'm now able for the 1st time play 10ths on the microArranger.
Previous to this, I was only able to dream of doing that on the Steinway.
Now that I finally own a Korg I finally appreciate what Korg arranger fans have been touting about regarding Korg's dynamically 'live' vs the CD polished sound of Yamaha arrangers. I personally appreciate having both brands to select from, or combine with when playing.
I had the same issues with the Korg microWorkstaion/synth (same 61 note keyboard)...pianistic playing, in either hand, is a challenge, and tiresome, and though it is nice to be able to reach 10ths on the microARRANGER, it is terribly disappointing if one is unable to transfer them over to one's main axe. Perhaps use the microARRANGER as a controller?

I didn't find the microARRANGER to be as dynamically
different from Yamaha's clean, smooth, highly detailed polished CD sound, as I did the PA2X/3X...the itty bitty Korg is using older PA-50SD/PA-80 technology, so it hasn't quite got the sound definition of the newer Korg systems, but hey...whaddya want for 400 bucks?

I'm only hearing on-line demos, so I may be more impressed once I hear it in person...there's a trip to Halifax coming up this month, so I might just get the chance to try one at Long & McQuade in Bedford, if they have one, of course.
Have fun Scott, and it is good to see you with one as you can guide the others as they wend their way through Korg's distinctly different way of doing things...and who knows? You might even grace us with a demo, of comparable quality to the one that was previously posted by one of your enthusiastic Korgian compadres.

May all your octaves stretch into 10ths,

Ian