For the sake of accuracy, I shall list what it is about P5 that I find makes it a better choice than P4. 1. The rendering engine has raytracing - allowing reflections and refractions and freedom from the (my opinion) inferior shadow-mapping and the associated hard-to-adjust shadow-cams. The speed of rendering (with optimum settings) I find to be faster than P4. There is no shadow-map calculation when raytracing. This must be counted in the rendering process. 2. Polygon Smoothing - when properly applied improves the figures' appearance. I see a lot of negative comments about this feature. If you apply it to everything in the scene it will be a render-time disaster. I only use it on main character figures like V3, M3, Judy, etc. It adds little-to-nothing to the render time. 3. Improved Library interface - It is a lot easier to add figures, props, poses, etc. with this much-improved menu system. 4. Python support - This is a great feature - open modularity for a wide array of functions. ProPack has Python, also. 5. Materials Room - Procedural textures in P5 are amazing. Easy to use and capable of an astronomical amount of combinations with or without texture maps. The procedural textures are often many orders of magnitude faster at rendering than even a tiled texture-imagemap. 6. Dynamic Hair - I am just starting to use this feature. It seems to work fine, for my first few uses. I have not used Dynamic Clothing yet, so I am unable to comment on it. So - I have stated what I find good about P5. It crashes far less than P4 and PPP, at least for me. A crash is a rare event. It is not slow, nor a resource hog - in fact is faster and less of a burden on the system, at least for me. It does have some sort of RAM memory leak, which shows up after a long day of rendering and requires a reboot. This is the most obvious flaw I have noticed.