Differences:
- better navigation/zooming (tap-drag for navigation, doubletap-drag for loupe style 1:1 zoom)
- better image scaling quality
- more supported image/cb formats
- does webcomics
- does plain images, too
- has support for annotations
- the development versions have support for text/html formats as well
- openGL accelerated (well, not much use on N800/N810s, but still)

As it's python-qt, it is slower than cbrpager on a N8x0 Diablo NIT, from what I understand on RX-51/fremantle it will be a lot quicker than cbrpager.

The current package in extras-devel is very raw, I wouldn't recommend it for day-to-day use, it's more of a tech-demo. I managed to include a fairly large default cbr in the package, that's where the extra size comes from. It will be gone in the next release (replaced with something more reasonably sized, that is).