Sorry, I haven't used one. I change her litterbox every 3 days or so when my kitchen trash gets full...so then I dump the litter in there and take it straight out to the garbage can outside. Then there is no smell in the house at all.
I had one of those around three years ago. Maybe it's changed or gotten better since then, but after a month of trying to use it myelf, I hated it. It's been in my basement ever since, never been touched again.
Hopefully you'll like yours better than I did. But, the poop always got stuck in the turner, and became full way too fast with three cats in the house. I just found it easier to run their bag out to the garbage after I cleaned their box. Good Luck with yours though.
This product is amazing. I have had no issue with it. I have one cat and it save me from daily trips out to garbage can. My garbage can guy will thank me for not stinking up the can. I have not had the knob stick or anything. It works as promised.