The big one that I've experienced personally is database corruption. It happens and it is painful. Aside from that, it's pretty slow compared to more modern SCMs.
If I were you, I'd recommend moving to at least TFS. The integration with VisualStudio is just as tight, it is much speedier, and the idiom is pretty much the same. I've had no problems with it in the 4 years I've been using it. Perforce is expensive and that's probably not something to toss around in an interview.
