Ok, I will repeat myself a little from the comments section, but I have made certain points clear. Obviously, I don't like this iteration of the mystic. I liked it much better in previous installations, and I think that the class is pretty broken. As it is right now, I do not want to allow it in any of my games without some heavy improvements.
My arguments, summarized, are:
1)Über-flexibility of the Psychic Focus. The possibility of rather big, unlimited benefits from it is baffling. Right now, there is no resource expenditure with them, so you have all of them whenever you need it except in combat.
Proposed fix: I would suggest 1 change of focus by short rest, much as the fighter's features.
2) Power creeping of several disciplines. Adaptative Body singlehandedly destroys from level 1 any resource management in any survival adventure (no breath-no sleep-no eat??? Without even expending resources?? Why we even need a ranger?). Brute force can manage to make stupidly high amounts of damage, bypassing the limits of PP expenditures by using several effects on different timings. Most Wu-jen disciplines, like Mastery of Force, are bags of holding of massive powers, as it contains powers worth 8 spells.
Proposed fix: Make disciplines a little less powerful. Sever some of them in two or three disciplines.
3) Psi Points progression is counter-intuitive and annoying. Come on, people. There is absolutely no easy way to remember this. The increases of PPs are insane. I know that they are the same of the Magic Points on the DMG, but they are clumsy.
Proposed fix: A real improvement over this would be using "Psi Points Dice", much like Hit Dice, that would increase with Intelligence modifiers. The dice could even increase at certain levels (first you have a d4, then a d6, then a d8, then a d10, and last a d12).
4) Psionics after 11th level ignore concentration. The only real benefit of the Mystic past 11th level is insane: ignore concentration with Psionic Mastery. Also, this mastery isn't tied to the order's disciplines, so you can choose anything.
Proposed Fix: Revise this rule. Concentration is, right now, the only thing that prevents caster supremacy.
5) Soul knife: it seems weird within the other orders. The only real distinctive role is to use magic (psionic) knives. It sucks, people.
Proposed Fix: should be a thief or fighter archetype, not a Mystic one. This way, you shouldn't worry about giving Order Disciplines some relevance.
6) Psionic as magic. Why? Psionics in previous installations were independant of magic. Psionics working as a different power source made sense. If not, they are only weird wizards.
Proposed Fix: Make psionics independant from magic; many of their principles work nevertheless, and tie them to the specific effects (an elf has resistance over mind control, no matter the source). If you keep the powers below the choke point, this shouldn't be a problem. Magic isn't precisely weak, right now.
7) Potent psionics. I'm a little bit tired of anyone having better damage on weapon attacks than a fricking fighter "just because they don't have extra attacks". Fighters (or maybe Rogues) should be top-notch here, not at the bottom.
Proposed fix: Potent Psionics should only be a Psi powers increase. You can give the extra dice of damage to the soulknife archetype only, and made that archetype a fighter's one.
8) Psionic mastery is moot. Aside from cancelling the concentration mechanic (huge boon), is just more Psi Points.
Proposed fix: Make mastery matter. Don't give extra PPs, give some huge benefit (like bypassing the Psi limit of a discipline power) or extra effect ("Mastery Power") to the tied disciplines. And tie that disciplines to the Order's ones. Another possible fix is giving permanently the Psychic Focus.
9) Lack of Archetype Disciplines relevance. This is a neat idea, poorly implemented. If you have disciplines tied to an order, give them some relevance, much like the Wizard Schools.
Proposed fix: You could easily fix this. Maybe Psychic focus work only with them? Maybe giving a psychic focus bonus permanently whenever you gain a Psionic Mastery feature? That would be thematically appropiate. And at later levels, gaining the focus bonus isn't as game-breaking as it is in the early levels.
10) Later levels lameness: right now, the Mystic is in a very rough draft form. Past 11th level, the only relevant thing is ignoring concentration, something that most DMs would banish at sight. But there isn't any real reason to keep being a mystic past that level. This leads to multiclassing more than on any other class. By 11th level, most classes have some neat power that further specializes them. This is tied to the general lack of cohesion of the class.
Proposed fix: Give the mystic interesting toys to play. Real ground breaking powers tied to their orders: Make telekinetic ones flight at will, the telepaths beguile the masses, the immortals revive, etc. I don't know. Neat powers.
11) Discipline Learning: There should be an option to learn a new Discipline without gaining a level, much like the wizard does. And even you can play with rules for researching and creating entirely new Disciplines. It's weird that very intelligent people don't do that.
This should be a neat class. I like the sci-fi flavor, the powers, etc. But right now it has a poor execution, and it is badly broken. I really don't like the powercreeping of several Unearthed Arcana options. Some of them are brilliant (like the first Feats, the Demon magic, or the clerical spells, like Ceremony). As it is right now I don't plan to allow them on my tables.