Biggest peeve is that I frequently hit the arrow keys on the bottom row by accident. Not being very good at using them on purpose, this completely throws me off for a second or two.
Minor annoyance is that the modifier keys sometimes stick. I don't think they're physically stuck; more like a firmware glitch, so that it's as if Caps Lock is on (mine's remapped to Ctrl), or I get accented characters as if Alt is stuck.
I still have trouble switching between the straight matrix layout of the Kinesis and the staggered layout of traditional keyboards, which I continue to use at home. Nothing major, but definitely some reduced accuracy.
So my experience is decidedly mixed. I'll keep at it until the end of the year at least, but I'm not convinced it's any better ergonomically. In fact, I've had some soreness in my left thumb that may be related to the new keyboard.
Oh and it is missing functions keys which means I could never use this.... The kinesis has crappy function keys but at least it has them. Can't program with an IDE without then.
There are 5 rows of keys on each hand, just like a standard QWERTY keyboard with a function key row, you just have to place them along the bottom row instead of the top. The problem, I guess, is that there's only 10 keys along the bottom row, but you could place F11 and F12 on one of the many extra keys. Keep in mind they're programmable, and you can have different layers and modifiers that just exist in the keyboard itself.