There are a few things it's missing. The built-in file searching, last I checked in version 0.5.2 I think, isn't working correctly, and it doesn't have have Thunar-style "custom actions", and it doesn't let the directory tree sidebar pane and the location bookmarks/drives panes show simultaneously.
It currently has no "trash can / recycle bin" feature, but the developer has said he plans on including it soon, which I wouldn't have minded either way, even though I do prefer to have it, because I have occasionally been in a hurry and gotten rid of something I shouldn't have. And I'm sure that's why the "really delete selected files" warning bugs you on each and every file deletion command, but when you go through your files cleaning up as much as I do and have your own system for saving yourself (in the way of a snapshot backup) the message jumps from extremely irritating to insulting, and there really should be a way to turn it off. I will get around to getting this message to the developer eventually, once I take the initiative to figure out how. Be my guest to beat me to it.
But, despite its imperfections, it's extremely fast and light (it starts instantly even on slow systems) and has a clean simple attractive interface. It's my favorite Linux file manager currently. For file searching, until the developer fixes it, do what I do, use catfish or some other tool. For "custom actions", learn to bash script or steal some batch scripts other people have created and create desktop files to the bash scripts, then open the files using Pcmanfm's "open with", and there you go, your own custom action that is as advanced as you want it to be (there is practically nothing you can't do with a good bash script; I'm working on one to attract women, so far it only works on hardcore Linux fangirls, but on the plus side at least I benefit from the knowledge they bring to the table; I'll get this thing licked yet... the bash script).
And though I gripe about having to choose between the tree and the location bookmarks, at least it HAS both of these features to toggle between, which is more than I can say for some file managers I've tried. And I should mention that the tree pane has actual functional right-clickable folders with the same functionality as if they were in the right "file pane", which is something I expect to happen but doesn't in some other file managers I've tried that had tree view.
So, I give it an excellent, whether some of the problems I mentioned are fixed or not. I've tried pretty much every file browser worth trying for Linux and this was the one that stuck. I was fortunate too that PCmanfm is also part of LXDE, my favorite Linux desktop environment.