"We first saw Sennheiser's noice-cancelling PXC 450 cans at CES, and while the company missed its March ship date by a couple months, it looks like it was worth the wait -- the first reviews are pretty positive, apart from the price. PC Mag says the sound quality "blows away" its Bose Quiet Comfort rivals, although the low-end is a little exaggerated for audiophile tastes. The Talk Through mic worked as advertised, and even the styling won praise -- rare for a pair of big cans. CNET felt the same way, raving about the crisp high end, excellent noise reduction, and passive operation capability. Overall, it seems like Sennheiser has a winner on its hands -- if it would just do something about that fat $450 price tag."
I've personally never been a fan of large headphones like these. My ears must just generate too much heat and I end up taking them off within 10 to 15 minutes. But, if you like these style of headphones AND money is no object, these appear to be a great pair.