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!
Only thing is, you do need the right kind of mousemat, or it jumps around...
When told about them, was under the impression you could say good bye to skanky mousemats, in practice anything slightly shiny is a disaster. Cheepo dark blue cloth like one from PC world does the trick.
I've cast away all mouse mats, that's part of the great attraction, in addition to the balls clogging up on ball mice. I use various (Logi and MS) optical mice on a mixture of oiled and varnished wood and I have no problems.