My first impression on the monk is that (like in 3E) it gets a large amount of mostly arbitrary class features that sound much more impressive than they are. Though thankfully they are proficient in unarmed strikes now. Overall only their different maneuver list and the 1/day stun attack make it meaningfully different from the fighter.

My second impression is that the designers are getting carried away with "expertise dice" and are shoehorning all kinds of classic class features into something vaguely related to dice. I'm just reading over some of the longer powers maneuvers on the list and am wondering why on earth some of those require expertise dice in that convoluted fashion. The way this is going, I'm actually surprised that they didn't shoehorn all monk features (including ki) into expertise dice somehow.

Example: composed attack. Normally, when you have disadvantage, you roll two dice and pick the lowest. That is an elegant mechanic. With a composed attack, however, you roll 2d20, pick the lowest, roll 2d6, pick the lowest of that, add that to the lowest d20 rolled, then use either that result or the other d20, whichever is lowest. Try having a beginning player use that consistently; this is not an elegant mechanic, it's just rolling dice for the sake of it.