You know what else would be a good filter? DRM compatibility. I'm guessing that 90% of the "9.7 screen + epub" devices I'm salivating over are Adobe DRM compatible, but I don't see that right off the bat. I'm imaging three drops: Amazon DRM, B&N DRM, and Adobe DRM. (Yes, I know B&N DRM is Adobe-based, but it requires a GUI for entering name and credit card details.)
I'd personally prefer the filters all stacked vertically instead of horizontally scattered like that, but I like everything NEAT UND TIDY.