Hi and welcome to the forum. The answer to your question depends on whether you have closed the image file in Photosho since you di the Save as. if not you can step back through History. If that is the case, then open the History panel from the Window menu. If you have closed the file between the save as, and noticing the problem, you are out of luck. It is a good idea to use a different name when saving a PSD file as a JPG or PDF, because there is always the chance you will do a reflex Ctrl/Cmd s later on, and overwrite the PSD file. I have done it myself more than once.
Is there any way I can recover all that work or have I been hosed by this "feature"?
You have very probably messed up yourself; as Trevor mentioned others have committed errors on such operations, too, but trying to lay the blame on the application will do you little good.
If you save a copy off of a file you may want to check »As a Copy« when doing the Save As in the future, that way the open document stays the file it has been before.
I just ran into this, also, during my first couple of hours with Photoshop. I think Photoshop deserves a fair amount of blame here. If both experienced users and novices run into this, to me, it sounds like the UI can and should be improved! If I never flatten and save a PSD, I expect my layers to be there -- whether I saved as PDF before or not.
There is a multiple-step process that leads to the saving of a PSD file without the [ ] Layers checkbox set.
After saving a PDF, the next time you go to save as a PSD, make sure the [ ] Layers checkbox gets re-set.
If I never flatten and save a PSD, I expect my layers to be there -- whether I saved as PDF before or not.
If you save as a pdf but do not save »As a Copy« I think you should not try to blame Adobe.
I care less about blame and more about improving the UI. In this case, my guess is a fix would require, say, tens of hours for Adobe and would save a large multiple of this in users' time...