I bought a pair on my last trip because it's fun to watch the lights. However, that being said, they are not comfortable/easy to wear. As others have said, they're much heavier than the regular ears (both because the ears themselves are plastic with lights inside and because the battery/mechanism is located at the top of the hat. So they don't sit like normal ears because of the battery compartment...for me it meant that they kept trying to slide off because the hat was too shallow.
I wore/watched them over at Mad T Party and it was fun to see the colors, rhytms change with the music. However, it is more fun to watch the hats than to wear them.