Very light, great venting!
The Fuse helmet is very light! Once it's on I forget it's there. The adjustable venting works great. With the vents open I stay very cool and on cold snowy days, keeping the vents closed keeps me warm. The sound is great for this type of setup, as good as using the headphones from an iPod.
The only complaint (and the reason for the 4) is the earpads with the integrated speakers are a little tight. In defense of Giro and Skullcandy I haven't tried adjusting the straps much but the pads and more specifically the speakers inside the earpads put some pressure on my ears. It isn't painful, just a little pressure.
Overall very happy with the Fuse helmet, I would buy this again!!!