I love my six-speaker Zalmans, and don't find them to be heavy at all. In fact, they're the only set of full-size headphones I've ever been able to wear for long periods without my ears becoming sore on account of my glasses. My ears can get a little warm sometimes, but it really isn't a problem.
I find the sound to be superb, but then I'm not an audio freak. I was used to using cheap stereo headphones. My more-adept friend told me they're a little light on the low-range, but that doesn't seem to bother me.
The downside? No volume control on the cable. I don't mind adjusting via the software control panel, but having the control is a great convenience.