In the weekly game I play in the psi-warrior's whole shtick is
polymorph self into big ugly nasty thing and rip foes apart. Our DM has ruled that he cannot polymorph into anything he hasn't seen with his own eyes, but since he's now 14th level, he's seen plenty. His current favorite form is stone giant, not for the AC bonuses but the Str enhancement. He's not too worried about taking damage since he's got
claws of the vampire...
IIRC, his buff routine includes polymorphing to stone giant, maximized animal affinity x 3 (Str, Con, Dex), claws of the vampire, and expansion, and he's usually buffed by the druid with
greater magic fang. A larger-than-normal stone giant dual-wielding vampiric claws. Scary. He is eagerly awaiting an upcoming conflict with...fire giants.
This character is a monster. He regularly dishes out upwards of eighty points of damage per round on a (hasted) full attack, and he's topped one hundred in a single (hasted) full attack more than once. Add to that such abilities as
displacement and
dimension door, and, well, our cleric's player likes to complain about how psionic characters are broken

The two psionic player characters in our campaign ARE probably the two most powerful in the group, however.