I've used Psionics extensively and always will, I like the extra flavour it adds of having a character that can send an enemy sailing across a room with a thought. I DO however hate the physical ability basis for a lot of the powers. But a lot of you are forgetting the Psions true strength, endurance. A psion will still be up and kicking with a butt load of power points/PSPs left while his wizard pal is bone dry. With Trigger power and the metamind prestige class, running low on steam is not much of a concern. I have a dream of an epic level psion in a tower built entirely of crystal capacitors...
What bothered me the most was how limited the system is in reference to gaining powers. The rules don't allow for the creation of unique Psionic abilities and I can't stand that whole limited amount of powers crap. Which is why I don't play Socerers.
Also, why the HELL would a non-psionic character be better defended against psionic attack? That's like claiming an illiterate slave boy is better at defending against magic than an archmage! What were they thinking... At least mind blast works...
The Elhb solved some of these problems, but only let the character get more in his primary discipline. Epic Psionics allowed for unique powers, but they take a lot of time to create and integrate into a campeign.
But as for Psions being weak? Have you looked at TK? The violent thrust allows you to throw a large number of smaller objects in a single round that unerrigly strike their target. A Psion with TK could manage to throw 1500 arrows (weighing 3 pounds for 20 arrows) at the minimum level he gets the power and it would only go up from there. I have a Psion that travels in a wagon that carries nothing but a huge stack of arrows. And failing the arrow approach (do to damage reduction), I can always just throw the wagon at them.

What about dousing a legion of monsters in 500lbs of oil, or Psionically creating matter above an NPC's head?
Quicken Power allows the Psion to do some hefty damage with two powers/round, and with the PSP system he can use all of his power on multiple uses of their high powered combat abilities. Mass Concussion, and Greater TK to name a few.
I'll be the first to agree that the system needs some touches, but I think what they have is manageable with a few house rules. And that d20 roll for manifester level is an optional rule anyway.