Thanks for your detailed review zcregle, sounds like you're happy with your purchase.
Our Pono MTSH-C-MS has arrived a couple of days ago and we are really impressed by it. Holding it up against our customs, we think that the craftsmanship is right up there. All details such as the finish, binding and purfling lines are executed just as clean or even cleaner than on ukes that cost three or four times as much.
Most noticeable features, of course, are the beveled armrest and a side sound port. Along with the radius fretboard and smooth binding to cover the fret ends, these things really work for the player's comfort. Adding to this is the satin finished neck which many consider to be less sticky and therefore faster for sliding up and down. The neck might also be a tad thinner than on their previous models, but I'm not sure.
We really like the new visual concept that Pono has come up with. Because of new restrictions, they omitted all Abalone and Pearl and replaced it with a simplified logo, a wooden rosette, and no fretboard markers. This makes for an understated, but classy looking two-tone theme of Caramel and Chocolate, just the natural beauty of the woods shown off by a spectacular gloss finish on the body and the faceplate.
The only thing I would criticize are the strings - and that's certainly an easy fix. Still, I think the factory strings are not doing their instruments a favor. They sounded tinny and scratchy, so we quickly replaced them with Oasis Warm and a Thomastik-Infeld low G which provide a much fuller sound. Not quite as deep and rich as a custom Ko'olau, but you can definitely hear a resemblance.
All in all, I think the Master Series offers a great value with many features that can only be found in much more expensive instruments. With its arm bevel, side sound port, radius fretboard and a fast satin neck, it is extremely comfortable to play while at the same time just beautiful to look at. Now I just hope they will extend this new line to other models as well, especially their bigger sizes...