I've found that P5 is a little harder to learn, only because it has a lot more options. I admit I've had P5 for a year, but I still pose and compose scenes with P4, get everything set the way I want, then save it and open it in 5 for the final render. If I had to mention my personal favorite difference, it's the focal distance in the render, so you can have the main model be in focus, but the background is slightly blurry, just like a real photo would look. The materials setting are the next best thing just because of, again, the vast amount of options you have. There's my two bits. :) ~ Rich Oh, and speed? The more detailed you want your image the slower it's going to be. Simple render, just a few minutes. Focal point, lighting, AA, etc, mine usually take an hour or two to render. (Compare that with Bryce! Longest render time THERE was 72 hours!)