Lots of stuff here, but the basics of the class seem really exciting to play:
Use it to model characters like Jean Grey from X-Men or Eleven from Stranger Things.
No spell slots.
When you "manifest" your power, you roll a dice, and if you roll too low you take "strain".
Strain is cumulative, you get some choice in how it effects you, does things like give disadvantage on certain checks, reduces speed, prevents dodge/disengage action, etc.
Max strain increases with level. If you exceed max strain you die. But you know when you're at max strain and get to make the choice of whether or not to manifest your power and risk death.
Also, this reminds me a bit of the Kineticist from Pathfinder 1e. Not a copy at all, just some of the same ideas. Which is cool because I really loved the Kineticist.
I haven't bought or read it yet, but I'm loving the concept. It's got the resource management thing, so it will fit with the other classes in DnD, while still being something different and unique, as I always thought Psionics should be.
I've bought this and it's so long! 110 pages, of which 70 are the powers. It looks great but in classic MCDM style (Illrigger is super complex) it is hella crunchy.
The list of powers is two and a half pages long on its own