My one real pain point with it isn't so bad, but I dislike how perforce tends to work at a file level instead of a commit level. It's hard for me to make several related changes which all touch the same files, like a series of patches which all refactor the same area of code, but which I would like to review and discuss separately, and potentially revert some/all of.
It's hard to manage this with shelves, because perforce can't handle unshelving the same file in two different CLs. I could submit all the changes to a separate stream, but perforce streams just don't usually work well for us, and it's still hard to experiment by constantly making and rolling back changes.
I guess I'm probably only used to this workflow because I have experience with git, but this is the time when I really miss the granularity of a git commit (and I'm doing a pretty gigantic refactor right now... so it's hitting me quite hard).