Okay, all good points so far, but nothing to really swing me either way.
Psychic Warriors I have no problem with. They're powers really give them very nice options, and don't require scaling in most cases (in fact... I can't think of one that has scaling involved off the top of my head).
"Worse than Bards" is not that bad, really. Unless you're bias against bards (I was... I recovered).
The ability score requirements (I personally believe that you have to have the requisite ability score to know a power as well... it's just silliness to know powers that you can't ever even manifest on your own) are a harsh aspect of the Psionic classes, but strangely, I've felt the restrictions harder for the Psychic Warrior than the Psion. The Psion has some good power choices, and can gain great benefits by focusing in one field. He sacrifices a lot, it's true, but it's a similar (if much stronger) decision as the Wizard makes with specialization.
Power scaling is the worst aspect of psionics, in my experience. Damage powers are horribly degenerate as compared to arcane (and divine) spells of the same level. The upside of the better direct damage powers is that they are non-elemental, and affect (or are supposed to, I don't remember) objects fully. Oh yes, and the Concussion powers (which I regard as the "basic" direct damage powers) are Fort half, not Relf (unless it was changed int he Errata... I hope not), thus denying the Rogue/Monk the benefits of Evasion (but sucking worse against tanks).
Lack of components is a valuable asset that I've seen used to great effect in a few situations, and I can just imagine more (being bound and seperated from the equipment was the case that came to mind first). Of course the displays make manifesting a little less than subtle in most cases, though I can imagine that it would be hard to pinpoint who, in a crowd, had manifested a power, had you not witnessed the act.
I don't agree on the support spell item. Many of the more useful powers are range: Personal. I perfer instead to utilize the "Save or..." powers, as they are universally as good as their arcane counterparts (I think). I've always loved Telepaths for that very reason.
I guess the low number of possible powers per day (in comparison to the other restricted-knowledge classes) thing is supposed to balance out with the awesome (and unmatched) versatility of psionic manifestation. No other spellcaster can forfeit all of his low level spells in order to cast a handful of extra spells at the highest level, or conversely sacrifice a higher-level spell to cast multiple lower-level spells. Still, I think the designers put too much weight on how powerful versatility can be in a situation, especially when the psionic classes have such small lists of known powers to choose from.
And is psionic combat really useful at all? It's not too complex (I've seen much more complex home-brew systems that just lose the ease of the core mechanics), and it is neat flavor-wise, but really it's more of a burden than a boon. Has anyone ever really used psionic combat effectively in more than a very limited "psion-on-psion with noone else around" situation?
And lastly, Psionic feats, though sometimes awesome in their potential, are somewhat of an untapped resource. Many of the feats that are homebrewed even (or the ones that make it online) lack either "style" or balance, and while the core feats give awesome options (well, mostly for Psychic Warriors, 'cause Psions don't have enough feats), they just seem very... limited in their scope. Like all of the feats now, they lack more awe-inspiring high-level feats.
And what about the variable DC? Anyone like it more? Anyone actually use it (I do, but it seems like more rolling than many people would enjoy, and it adds a lot of chaos)?
Let's see... that's about everything I can think of.
Oh yeah, and the core PrCs just rock conceptually (I've never seen 'em used in a real game, though I have toyed repeatedly with the Soulknife just for kicks).