Truth be told, the only thing I've ever read in PSL was Day Planners, which of course is awesome, but then again I dislike ff in general, so my opinions aren't worth much. :derp:
DP is different because its format requires less actually reading and more imagination and interpretation while still conveying a lot of information and funny. It is less "work" to read and more stimulating at the same time.
It is also hilarious.