It's lots of fun! I wore mine for our entire week's vacation last year, and never had to replace the batteries. I'll proabably replace them before we go again this year, though.
I did have a rough time with the pin backs coming off, but when I went to a pin station to try to buy a couple of the rubber ones, the CM asked why I needed them. When I told her, she just gave them to me, even though I hadn't actually lost them.
Other than that, they're very nifty, and definitely add to the magic (that is, if you don't have a geek husband who's constantly trying to figure out where the signal transmitter is)!