Im starting a brand new game, but I didnt want to go into training until I asked this: Is it true from what I've heard from word-of-mouth that the PSI skills are useless?

I think they can be useful, but you will have to put some thought into your build beforehand. I recommend looking at the various techniques and choosing the ones that allow you to make full use of your psionics. Go with these two guides and look up the various abilities.

System Shock 2 - Psionic Powers (GameBanshee)

Analysis FAQ (Gamefaqs)

when upgraded properly, the PSI guy can be a freight train o' death, smashing all enemies in one hit and shrugging off high damage attacks like they were nothing. however, I would'n recommend choosing OSA in your first run, it's a bit difficult to manage.

PSI skills fall into three categories: entirely awesome, "meh," and entirely rubbish.

Really, there are no simply "good" or "bad" psi skills. They're insanely bad, insanely good, or ehhh whatever.

Look up System Shock 2 and PSI. You should find a decent psionics guide somewhere that will lay it out for you.