I have a litter locker and it's ok but not brilliant. I use it for convenience as I used to scoop into nappy sacks and dump them in the bathroom then take them out to the bin when I left the house. Except I'd sometimes forget and they'd be there all day! Not too stinky given they're in nappy sacks and my 2 aren't overly stinky
. With the litter locker I still scoop into the nappy sacks but now dump them in the litter locker. There is no filter or anything in the litter locker - it's just like a bin with a thick plastic bag. You turn the handle to twist the bag and effectively seal it. You are supposed to just scoop straight into the locker but I'm sticking with the nappy sacks (more conveniend for me than lugging the locker from the bathroom to the tray in the living room and only cost 29p for 100!) and am glad I do so as I've had the bag rip a few times and when you get to the end of the refill sometimes there's not enough bag to seal properly. I find I need to empty it about every 5 days or so and it does smell a little when you lift the lid and I have to wipe it out with some disinfectant/deoderant each time I empty it to stop the plastic retaining the smell. And as you say, the refills are expensive and only last 3-4 weeks (with 2 cats). They aren't fragranced either.
It does offer some advantage if you're like me and don't like to have to go out with the soiled litter every time you scoop, but I think it's expensive for what it does. I was expecting it would have filters and stuff inside to deal with the smell but it's just a fancy plastic bucket really!
