Fmdog, I don't have to charge it. It charges itself. It sits on the charger when not in use.
I don't follow up in corners, but to be perfectly truthful, I'm not that fussy and don't inspect every inch. It looks clean enough for me.
It doesn't work in all situations, though. I don't use it on my enclosed porch, because I have a fern out there that sheds as soon as it gets bumped into. So it might clean up the leaves (or whatever they're called) that have dropped on the floor, but would produce even more mess. For that room, I use my Dustbuster.
Also, the roomas don't go up stairs, so they really are meant for one-floor homes. But I like it a lot for my apartment.
I can't imagine what you could get for the $900 model that's so much better than the $300 model. Good grief, does it figure out your taxes for you?