I never had P4 or PP. I've only owned P5, so I can't really compare. Like many, I struggled with a lot of issues and it does have a bit of learning curve. In fact....I still haven't mastered it. The material room is great and many merchants are beginning to take advantage of the material room capabilities (RDNA, Sixus to name two). Multiple runtimes....something you can't do as I understand it, in P4. Multiple folders....three or four deep....in your poses, props and other main folders. The ability to finally import P5 .pz3's into Vue d'Esprit 4, makes P5 hard to pass up. Did I mention the material room? Get it, but be prepared to get frustrated and to spend some time learning all the nuances. BTW, I found it stable after SP-3 and never did update to 4 :) I pretty much know what I can and can't do and rarely have problems with it anymore.