By far one of the most complete, organized and useful toolsets for soloplaying any RPG on your shelf and it is improving constantly. I cannot recommend it enough and it has become the sole tool I use for playing RPG games alone. 
It's like a Virtual TableTop program designed from the ground up for soloplay and you can tell from the way it functions that PUM existed as its own thriving system and the companion is an organizer that allows the Machine that Unfolds to function fast, intuitively, and effectively. 
It's full of excellent tutorials and while the interface can be overwhelming at first, if you take your time to get to know it, it'll feel like home in no time at all. 
If you are interested in soloplay you've got to give it a shot.