I played a Psychic Warrior... up until about level 15 when he died a few months back. I though he was a pretty cool character, but mainly because of the interesting background, history and personality I had created (which could probably have fitted any class). I think the Pros and Cons of the class will really depend on the type of campaign you play. Some random thoughts on the matter:
* My character was a convertee from 2ed where he was just a plain fighter. Consequently, he began his psi warrior career at an accelerated level. I never had to start out first level with the very lame selection of power points and 0 level powers. By the time I started, I already had a small body of powers and some PSPs. I imagine creating a new psi warrior is rather tough. A bit like a monk I suppose.
* Yes, the comparison with the cleric is tough... but then the cleric is a pretty powerful class. Despite the same BAB and HD, though, a PsiWarrior is more likely to have a higher Str and Con, whereas the cleric is more likely to divert higher scores to Wis and Cha for spells and undead bashing. The Str and Con of a PsiWarrior help for both power-use *and* combat. Consequently, I found the PsiWarrior was a stronger straight combatant than a cleric. However, we play in a high-magic campaign, and Tomes are not uncommon and so this advantage was dimished as such (eg, our party cleric has both Gauntlets of Str and a Belt of Con, overcoming his physical shortcommings).
* The Psi feats can be very useful. Yes, some of them have a cost, but then with crystals you can really boost your available PSPs. Our party Psion spent quite a bit of time and resources in gathering a good selection of crystals... if my PsiWarrior had done the same, he could of used some of the gnarly feats more often.
* Depending on the flavour of the campaign you play in, being psionic might have certain benefits. In our game, psionics is treated fairly similarly to magic. In a different game, where psionics is less common and treated quite different to magic (either arcane or divine), your PsiWarrior is going to be more of a novelty and more useful.
Down sides I found to being a PsiWarrior were generally the selection of powers available. Getting to the levels where you have 4th, 5th and 6th level powers is all very well, but on many occasions I didn't have the requisite stats. A slightly more expanded selection of powers would be nice (no need to go overboard or anything), and more high level powers using STR, CON and maybe DEX as the base stat rather than INT, WIS or CON.