A ChairBot...
http://www.newlaunches.com/archives/hubo_fx1_chair_bot.php
Whoa! That would make office chair races totally different!
The only advantage over a powered wheelchair is that it can ascend stairs or stair-like terrain. I should say, that there is the possibility that it could, since the demo video only shows it slowly walking forward and painfully slowly sidestepping and turning.
The idea of using it for people who are mobility-impaired is a good one, but the idea of a soldier riding one of these firing weapons? The weight of the required armour would make it ponderously slow. And I don't want to be in a firefight with large guns (since these get taken out first) in a ponderously slow vehicle!