Perhaps this UA is lead in to a 5e Lords of Madness book? Or maybe it's just a tie-in to BG3 with all of this mindflayer flavor.
Aberrant Mind.
Invasive Thoughts
A nice bit of ribbon with practical uses. The two way back and forth is especially keen.
Psionic Spells
Well, this is going to be the decisive factor. Not only do they get more spells than any other Sorcerer (and people will tell you that Sorcerer's don't get enough), but they also get some exclusive spells too. Let's see what is juicy:
Arms of Hadar. A Warlock PBAoE spell that targets STR at level 1. Deals some damage and prevents reactions! It's good because if you are being swarmed at t1 of the game, the creatures who are doing so will favor DEX over STR. It's bad because STR tends to be a good save of most big and beefy things who like to squish casters, and you should never go out of your way to make it work.
Dissonant Whispers. A decent control spell that you might be able to score some OA's for your party with. Targets WIS, which is nice because those beefy brutes who would resist the above spell tend to fall for this one.
Calm Emotions. A CHA targeting spell that might let you change a combat encounter into a non-combat encounter.
Detect Thoughts. I wouldn't go out of my way to pick it up on a Sorcerer, but for "free" it's a nice option to have.
Hunger of Hadar. I guess if I can't use Fireball for some reason, you could make this work as a choke-point.
Sending. In the same league as Detect Thoughts.
Compulsion. Like Dissonant Whispers, but with more fine control. Not super excited by it due to slight redundancy.
Evard’s Black Tentacles. Solid control.
Modify Memory. Now that the Sorcerer has it on tap, expect more shenanigans and attempts to cover them up.
Rary's Telepathic Bond. A good ritual spell, but I don't know how many people are going to be chomping at the bit to actually cast it.
So the scorecard is 5 great spells, 4 OK spells, and 1 spell I just don't care for. But still 9/10 additional spells is basically the best Sorcerer Origin that you could pick.
Warped Being
So they get all that and more AC too? As if the Dragon Sorcerers didn't have enough reason to be envious.
Psionic Sorcery
Basically, all your extra spells end up with a free Subtle Spell metamagic thrown in on them. Oh, and you can apply another metamagic on them, because you didn't actually use metamagic on them. Also you cast them at an effective profit, because it only takes 4 points to cast a level 4 spell this way, but a level 4 slot is worth 6 points.
Come on now, this is just Salting the Wound for other Sorcerers. Give them a Psionic cantrip with some bonus damage or something else more tame at this point.
Psychic Defenses
Remember those Dragon Sorcerers, crying in the corner over there? They have to spend a Sorcery point to get this benefit, don't tell them about this, I don't think they can handle it anymore. Maybe this is actually a test bed for Advanced 5th edition, and they are seeing what we would let them get away with.
Revelation in Flesh
Instead of having a permanent flight ability (or similar) they have a temporary flight power. And/or Swimming power. And/or escape power. And/or See invisibility power. There was a glimmer of hope at the beginning of this paragraph, but that has been quenched. Only the morose silence of the Sorcerers remains.
Warp Reality
It's an area damage tool that doubles as a 1 mile distance teleport. Which can teleport everyone within 20' or you. That's like a 9th level spell effect right there. You could teleport an entire platoon within a castles walls with one turn of set up.
I expect capstones to be over the top at this point, but you could divide this power in half and still have something worthy of shock and awe.
Thoughts.
I'm reminded more of the Alienist from 3.x, than a traditional psionic character. Especially towards the endgame.
I've said many times over that any Sorcerer Origin could serve as a Warlock Patron, and vice versa. This is the pudding of proof. Maybe when 6e comes along they will finally merge the classes, which should incidentally fix most of the problems the individual classes have.
One nice bit about the fluff for this class is that it explicitly states that you can choose how this stuff manifests, if it does so at all. There are more than a few people distressed that their high charisma character has a "horrible deformity" like dragon scales or the like.
Now for the elephant in the room. I really do think that Sorcerers could use more spells. I think more along the lines of 5 and a Cantrip is a good number, especially if they are still going to get those nice mutant powers like flight. Other than that, damn Psionic Sorcery is good, it's like they buried it under extra spells to sneak it past us or something.
Now for something hopefully less contentious.
The Lurker in the Deep.
Split Your Lungs With Blood And Thunder!
Expanded Spell List
Create or Destroy Water. If you are trapped out on a ship in the middle of the ocean, it will prevent you from dehydrating. A solid meh.
Thunderwave. A slightly weaker Arms of Hadar, which Warlocks already have access too, but it's free, so there is that.
Gust of Wind. That ship you are trapped on? Well now you can get it back to the port. Has some some potential for crowd control but expect less from it the more levels you have.
Shatter. It's alright for a level 2 AoE damage spell. Oh snap, this is already on the list, what's up with that?
Lightning Bolt. The Luigi to Fireball's Mario. Not too bad considering Warlocks don't normally have access to either.
Sleet Storm. This is a bit of a stretch, and not particularly interesting to boot. I know Elemental Evil is a different book, but Tidal Wave would have had more traction here. Maybe even Water Breathing?
Control Water. A fun spell.
Evard’s Black Tentacles. Probably more fun than the other option.
Commune with Nature. This is another case were we see the lack of Elemental Evil spells really sticking it to this subclass.
Cone of Cold. Yet another iffy one. Could have gone with Conjure Elemental at least.
So 3 good spells, 3 OK spells, and 4 stinkers. A spell list that really makes you feel the PHB+1 crimp.
Grasp of the Deep
It says "Tentacle", but the gray box implies that's just a cosmetic thing. It's mostly an alternative to Hex that throws in some soft control, which cribs the mechanics of Spiritual Weapon. Of note, this is a Per Day power on a class that mostly functions on a short rest cooldown. Also of note, this doesn't grapple? It does slow, but you would think it grapples based on the name.
Scion of the Deep
This is the rare case of a power where I would imagine it doing more bad for you than good. Mentally communicating with Aberrations and Monstrosities has got to have some negative side effects.
Fathomless Soul
Standard Swimming bonus for aquatic themed subclasses. The resistance to cold damage is questionable, but at least it provides a use for those times when you aren't submerged.
Guardian Grasp
You can sacrifice your spiritual Tentacle to cut the damage of an attack in half. Given that you have an extremely limited number of Tentacles per day, and they have to be within reach of the target, this is really lackluster. It really makes me wish for the Inky Escape ability from the Happy Fun Hour.
Devouring Maw
This, on the other hand, is much more impressive. Some area denial, some control, and a significant source of temp HP to boot. At higher levels, you could even use it as a kind of bubble around yourself so that nobody wants to get up close next to you. And it follows the short rest play pattern of the Warlock as well.
Unleash the Depths
I think is the first Warlock ability that manages to directly manifest some portion of it's patron, that's rad, and a fitting capstone concept. They should really do more abilities with this concept.
Unfortunately, it's functionally kind of weak. Once per day you can get the equivalent of a 6th level spell. Which is limited to a kind of teleportation or a kind of smart AoE damage with prone. I suppose that is the problem of having your capstone at 14th level, it can't be all that good.
Thoughts.
Even when you control for the absurdity of the other subclass in this PDF, This subclass suffers greatly from the lack of Elemental Evil spells. Additionally, the tentacle thing should be limited to two or maybe three per short rest. Other than that, I more or less expect this thing to show up in print.
Spell!
That's right, there is a new spell in the UA. I expect most people overlooked it do to the mental fatigue of having those subclasses thrust upon their eyeballs.
Mind Sliver
This Enchantment attack targets INT (whoa) does 1d6 scaling psychic damage (ok) and bestows a 1d4 penalty on the targets next saving throw (OMG).
It's basically the new must have cantrip. Heck, they could nerf it twice over and it would still be the new must have cantrip.