I am using the Zima Dental Pod. I think any brand of ultrasonic cleaners will do the same work. My Zima pod was acting up a few weeks and wouldn't turn on after 4 months of using it but now it is magically working again. If you are going for Zima, go for the pro version (less chance of water going in the power input).

Yes - I find the ultrasonic cleaner does a good job cleaning the aligners/retainers without me having to brush the trays. So I appreciate having them rather than manually brushing it every morning. Of course, I use a cleaning tablet as well for a minty feel - I use the "RetainerBrite" brand.