Ultimate Psionics is an absolutely wonderful product, filled to the brim with mechanics and fluff. You will lack for neither as you scour each page with delight and anticipation, looking for ways to add some flair and flavour to your standard Pathfinder games. Each class, prestige class, feat, skill, item or power has been meticulously designed and fleshed out - you will never feel lacking for anything.
Want a ranged character? Look no further than the Marksman, a psionic powerhouse without equal that puts Ranger (Archers), Arcane Archers and Gunslingers to shame.
Is melee more your style? The Psychic Warrior, Soulknife and Aegis, these brutes can go toe-to-toe with any Fighter, Magus, Barbarian, or Ranger any day of the week, and trounce them handily.
Prefer casting spells? Want to give Psionics a try and manifest powers instead? The Psion, Wilder and Dread will fill you with delight, and make you the envy of the table as you casually warp minds, instill terror and decimate your foes with ease. All of this and much, much, much more.
Not enough? Try pages of unique class archetypes, cleverly designed prestige classes, racial traits (and new races!), feats, powers and more. You can tell the developers clearly love their psionics and it shows. This is one of those rare occasions where I can confidently look someone in the eye and say:
"Yes, this is a third-party product, and yes, it is every bit up to standard as the core rulebook. On top of that, I will say that Ultimate Psionic is actually better than the original, everything is enhanced without being overpowered or cheesy. This is how third-parties should be designing their works, and those folks at Paizo? They could take some serious lessons from Dreamscarred Press on how to make something really intense and fun without overkill!"
Ultimate Psionics is a standard book at my games these days, it has everything we need to run mixed classes and full-on psionics adventures, with everything else in-between. If you enjoy psionics, want a change of pace or just feeling like getting over your previous psionics bias, take a good hard look at Ultimate Psionics.