I've owned one for over three years. I have the MSX1 and yes it is noticeably heavier. I was wearing a Shoei RF1000 the weight difference was huge. Unbearable? No. There is basically just a couple of vents (chin and above head) so its pretty quite however it does get a little warm on those extra hot days. It's shape is bigger due to accommodating the mirror system. You can see pretty far away and it's visible enough for me to see anything behind me. You have to spend a little time to adjust the rear view mirror portion depending on your riding/head position.
This is the only helmet I wear and I love it but there just a couple of cons I have: 1. If you keep your helmet inside (which I do) and then take it out on a hot/humid day the mirror and back is all foggy to hell until it warms up. 2. My rear view mirror is now loose and when I get on the throttle it tilts it so I have to adjust once I slow down.
Overall, if you can get past the heavier weight, weird shape, and the cons it's a really great helmet. I'm actually ready for a new one and they have an R version which is made with carbon fiber.
