They're great. I went to the other end of the spectrum from Henry, mine is a Logi MX700. It's not particualry cheap, and I have no idea how it compares with the Dabs one, but I like it. Comfortable, enough buttons, it's got a rapid charger, so when you forget to put it in the charger for 2-3 days and the little red light starts flashing just putting it in for 5 min while you make coffee will keep you going for a a few hours.
I've just had to buy 3 mice for other systems and for those I've gone for plain non wireless optical mice. Much cheaper, and still a big advance over a ball mouse, but after using my wireless one having that wire trailing around gets tedious very quickly!