There really isn't a killer app. PPC games run faster than on a classic if using a NG machine.
Plus it works out cheaper/better value than buying a PPC card. Runinuae is okay, but for some reason I can't get two USB joysticks working at the same time, and some games run slower than on my A1200 060 using WHDLoad.
I mainly use it for Scumm and the odd browsing.
Under WinUAE with AmigaOS 4.1 FE it's fun to run, the browser is better than OS3.9 and it runs faster than my A1200. But no 3D as there is no Radeon support.
Okay to play around with but that's it.