Okay, I have tried all three of the psyker classes and find them all fun. There is always room for improvement, but he is a lot of fun to play. My absolute favorite is to walk into a room and nuke the whole area with Firestorm/Hemorrhage. But you have to play him carefully because he can dish it out, but he cannot take it.
That said, he has a few problems.
1) The Force staff/Force rod show that they cool down Warp Heat by 15 with every use. The Pyrotechnic Staff, Wyrdvane staff, Warp Rod and Telekinetic Rod do not show that in the description. Sometimes they cool Warp Heat like the others, sometimes they don't. That has to be a bug. Are they supposed to or not? If so, that needs to be in the description. If not? Then they need to stop doing it.
2) Cover- OMG cover... He CANNOT use cover. Oh, he can hide behind things, but then every shot he fires if it isn't an AOE spell hits the cover instead of the enemy. I cannot count the times I have used Molten Beam only to fry my own cover with it, leaving me to stand there looking stupid under enemy fire. He sticks to the wrong places, he cannot shoot out of it... Cover sucks with him. I just stopped trying to use it for the most part.
3) We need a better description of the Warp Anomalies. I assume one will be there for launch. I didn't even know there were beneficial ones until today. I ran over one by accident and it helped me! I was shocked. Then I ran over another and it ate me.
4) We need 24 skill points to unlock every psychic power enhancement at the moment and we cannot even unlock the debuffs until level 7. That needs to be better explained. Also, do the Heat or the Damage over Time skill trees help with psychic powers? It is hard to tell.
5) Can we get a targeted anti-tank spell of some kind? Please? Those Leman Russ tanks are no joke. I try to Molten Beam them and I get fried/run over. Hemmorhage doesn't seem to do anything.
Still, FUN class. You have to play the Psyker tactically. You cannot simply run in and stand under enemy fire like a Crusader. Well, you can, but you die real fast.