I've noted that they are considered favourably by people on the forum. I would also love to try them but they don't sell them where I live. I have tried the toothpaste but my cats didn't like that particular flavour.
Here's a link to a thread which talks about other things you may wish to consider as well.
I've tried them before. The chews are pretty large so a cat has to really chew and gnaw on it to break it up into small enough pieces to swallow. It works better than something tiny like Greenies, IMO.