First impressions, all IMHO of course.
Spells? No thanks. Name them Powers or Talents or Abilities or something else. They can behave exactly like spells and interact exactly the same with Spell Resistance etc, but not spells. Psychics shouldn't be using wands and staves.
Undercasting? Ugh. Why not make them scaling UP instead of DOWN? When you have what is effectively a spontaneous full caster, why make them burn their limited higher level "spells known" for weaker effects?
Speaking of weaker effects, it sure seems like the attack/defense "spells" are woefully underpowered for their levels.
All of the classic attack/defence forms should not be "spells" at all. They should be like Magus Arcana. Start with 1 attack and 1 defense at 1st level, then pick from a list every 3 levels. They should be scaleable, not undercastable. They could be powered with "phrenic pool" points, which could be increased to pay for escalating costs of upscaled "spells". The current uses for the phrenic amplification could be moved to feats or another mechanic ("uses/day" or something), or have their costs adjusted to account for the greater number of available points.
Psychic Disciplines. Call me old fashioned, but I had hoped this would more closely mirror the classic disciplines, rather than be like Sorcerer bloodlines. Currently, this class is (again, IMHO) a poor-man's sorcerer. Telepathy, Precognition/Object Reading, Mind Control, Psychoportation, etc etc. instead seems more in line with what I think people might be hoping for. Lore? That just looks like an attempt to make a psychic themed sorcerer look more like a psychic themed wizard. Pain? Make an archetype instead.
Again, I have not studied the playtest document in depth, and all of these are just my first impressions after a quick read through. If I got something wrong mechanically, forgive me, I'll look at it more closely when time permits.