If it's the slightest consolation, I'm not entirely sure what several of them do, myself, and I'm going to have to experiment. From the release notes, the features are:
Feature: Added 24 more User Sample groups—now 32 total
This is pretty straightforward. When preparing user samples you can now use User Group 1-32, whereas before you were restricted to User Group 1-8. This makes it a lot easier to install a variety of sample packs from different sources. I've updated PXToolkit to version 1.1.3 to make this easy to do at authoring time, but you can take existing downloadable samples and relocate them by renaming the appropriate directory (eg: from u03 to u31 to move what would have installed in User Group 4 to User Group 32.)
Feature: Added “Direction Follows Loop” sample modes
I'd have to make wild guesses, so I'm either going to have to confirm some hypotheses experimentally or wait for official documentation.
Feature: Mod between tempo-synced LFO values when sync enabled
I'd have to guess that with tempo sync enabled for LFO, this means that you can now use a modulation source to switch among eighth note, quarter note, half note, etc. relative to the established tempo. That's a guess, so I'll have to experiment.
Feature: Crossfade added to forward/backward loops
Interesting. Again, something of a guess, but when using the forward/backward loops you could get audible discontinuities because the slope of the waveform is suddenly inverted at the start and end points of the loop. This sounds like it's intended to use the same sort of crossfade that smooths out discontinuities between the start and end in normal looping modes.
Feature: Sped up refresh of sample names following instrument load/delete
This one, thankfully, is self-explanatory. After installing user samples there's a process whereby the Prophet X scans installed instruments before you can use them. This process is now much faster than it used to be.