I actually have a fair bit of experience with disassociate anaesthetics/NMDA antagonists/whatever you want to call them. I have never taken PCP, nor do I desire to, but I have taken huge doses of ketamine and DXM. Dextromethorphan itself is a very interesting drug, and it has very different effects at different doses. Low doses can act as a stimulant, moderate emotional pain killer, or just enhance life. Higher doses are very different, and it then begins to act more like ketamine.
I first tried ketamine when I was working on my neuropharmacology thesis, we had it in the lab to anesthetize rats (yeah, it sounds horrible). It was a religious experience every bit as much as my first really good experience on psilocybin. However, it can also be abused when taken regularly for its mood altering effects. Chronic use of high dose DXM is not a really good idea, I know, but it can be used as a very constructive psychedelic when used properly.
I always remind myself that I can't make psychedelics do what I want, they will do what they want to me, and I have learnt to accept and enjoy what they can give. They are never a good way to get away from "yourself", which is what many people use alcohol, opiates, and even DXM for.