First, I wanna make my level of 'expertise' clear:
I've cleaned professionally for 20+ years (Daycares, law offices, bars), I have two teenage son and a messy husband.
I'm very familiar with a vacuum.
My husband bought this vacuum for the stairs on our new home.
1) I have a GREAT dislike for the new "Lithium Battery" crazy. First off, they are not as 'Green' as the hype tries to get people to believe. I highly suggest everyone read up on it. But the bottomline is Lithium must be mined and mining isn't something known for being 'Green'.
My other issue with lithium batteries is you can not leave the appliance on the charger. While this may not be a big deal with power tools it's a very bad idea with things like a vacuum used more in emergency cleaning situations.
Meaning, while you can plan ahead to make sure your power drill is charged before you use it on a big project, you can't plan ahead to clean up a coffee grounds, kitty litter or toddler related mess.
2) The 'dirt cup' is very, very small.
3) When you push the power on, there is a delay. The suction has to build up for a moment.
Miss the days you could just pull a dustbuster off the wall, it work immediately and you hang it back on the charger.
As for the stairs, I'm sticking to using a broom. It's more efficient and can be bought for much better price.