We've got one from 'Wiggly Wigglers' and it was working really well till our Border Terrier 'Gonzo' decided to chew the liquid waste tap off :?:. The result was one broken wormery and an extremely smelly dog.
I can highly recommend the wormery though.
The dog is slightly less popular at present. :?:
Just got one, about four weeks ago. That means I've got a heap at home, a wormery, two heaps on the allotment alongside a manure pile. Experimented with a snailery, found that idea in a Bob Flowerdew book, but it was crap. Going to do bokashi composting this summer too, see how that works out.
Anyhoo, seems okay so far. Worth the effort? Well, its not really an effort, so yes. Is it worth the effort if you've got a compost heap? I'd say so, for producing liquid feed and something better for potting. A small domestic heap produces excellent soil conditioner compost, but its very hard to get the heap hot enough to kill off seeds and pests.