I ordered one for my Dparents (QVC had a special offers + easy pay+ free P&P at the time)
They wanted something lightweight and cordless (both in their early 80s)
It does a really good job, I used it on all their carpet (stairs were a bit tricky as it was the standard size not the one for stairs or cars ) but I placed it on and dragged it back, worked fine.
Lights on the top tell you the level of charge
Easy to empty the bin filter easy to remove and wash.
Had to cut the hair off the roller ( I could've removed it but I CBA) my Dmum brushes her hair where she sits 
so it got clogged up, but after the first proper vacuum it was ok.
The cable for the recharge is a bot short for their power points but some of these are higher up. They keep the charger in one of the bedrooms and put it back there.
Its not the most attractive vacuum and you need to read the directions to assemble (once you've snapped the bits together you can't undo)
It's £180/£200 ish so there are cheaper ones but it fit the criteria for them.
I have a Shark , the vacuum head comes off easily (the suction is strong) and that (IMO) wouldn't have worked for them.