In general, Soulknife (the 3.5e class) sucks. It's better than the 3.0e PrC, but that's not saying much, since almost everything Psionic in 3.0e sucked.
You can make one that's playable, but only if you focus on your strengths. There's basically only one way to play a Soulknife, and that's as a hit-and-run skirmisher.
You get good HP and decent skill points from a good skill list, but you can't slog it out in melee, and you can't pass for a skill monkey either. You even suck at mid-range (since you can't make a ranged attack
and move).
One fix for this is the
Soulbow PrC. It's one of the few things to come out of Complete Psionic which doesn't make the game worse. (Don't buy Complete Psionic, the whole PrC is reproduced in the linked article.) It gives you faster enhancement progression, and you can choose from a better set of enhancements: shock + flaming + frost = hell yeah.
Better yet, you can keep a nice Bastard-sized Mindblade in one hand and fire Mind Arrows from your other hand, so not only does your range increase, your ability to deal with sudden enemy charges also improves.
What else can you do? Power Attack + Psionic Meditation + Deep Impact = massive damage every round. You can't do this until you hit BAB +5, and it costs four feats, but it's well worth the investment vs. highly armored monsters, like dragons. You'll need a good Str and Wis, but you'd want those anyway.
Psionic Body will make every [Psionic] feat toughen you up a bit, and you ought to be taking a lot of those, so it will add up.
In terms of stats, you need a decent Str, Dex, Con and Wis. You want to enhance your Dex as much as possible. Once you get into Soulbow, you will also want to enhance your Wis. Con goes without saying, every PC needs hp. Str is important until Soulbow or Deep Impact, at which point you care more about Dex & Con (both for staying power).
Cheers, -- N