I am not gonna argue about tastes and subjectivity here. I have played monk casually on the side since HW pretty consistently, although always as a second job rather than main. I love the job, but I never could completely optimize it 100% because it becomes way too galaxybrain for me. I feel this expansion has taken the cake for that though. Now difficulty and tastes will vary, so I'll talk about what I find problematic on a relatively high level in terms of rotation and/or usability:

- Having to keep up a short dot, a very short self buff, and a leaden fist upgrade buff, all at once at literally all times, is a LOT of layers to keep track of. The disciplined fists buff could really benefit from a gauge, easy to track, timer. Losing it is extremely punishing, especially during blitzes, which leads to...
- Blitzes are extremely restrictive in how to set them up, they need to take into account disciplined fists, demolish, and leaden fist. How you enter them and exit them, and when to use them properly, is not intuitive at all and full of novice traps.

Now for the rotation itself:

- The current monk rotation doesn't work above 1.95s (ish) on the GCD because Riddle of Fire is too short (why do we still have timers when we could just have stacks those days??), and suddenly allows for an extra GCD past that speed threshold. The optimal speeds make the rotation out of a proper loop and it becomes extremely galaxybrain to play if you don't want to go for a suboptimal rotation that tries to realign it every 2min (cf the "braindead rotation" on the balance). The rotation loops back again at 1.88s, which becomes suboptimal in terms of stat effectiveness.
- MNK is a crit addict job, which means getting too much speed means sacrificing crit, and staying at low base speed means potentially giving up good crit gear that also has skill speed (on top of not being able to get the 11th GCD under RoF). This means that the job is played optimally at speeds that clash hard with the design of the rotation/job itself: nothing aligns.
- The elephant in the room: we are seeing already double solar nadi openers because they prove more powerful than a standard lunar/solar, and I really, really doubt that it was intended by the designers. They made it so that phantom rush could not be used in the opener (only 2 perfect balance charges), and yet people are still finding ways to realign it on the 120s cooldowns because it's just better. This feels just wrong to overwrite nadi and still getting the most optimal numbers out of it.

MNK at high level is left in a very awkward spot were you just have to pour so much flawless effort into it that it feels kinda depressing. Maybe it's by design though, and it's meant to be like this. But the problems I quoted above are hard to look past objectively.