It does a wonderful job of cleaning jewelry.  My ring sparkles more than it did when I first got it :)
It is made of plastic and will break quickly.  Less than a year the on/off switch broke off and I have to use a toothpick to work the cleaner.  It was cheap machine, so I should have know it wouldn't last forever.  It works great, just be VERY careful with it to keep it from breaking.