Well, Sennheiser's Momentum Wireless, which costs a little less ($500) and adds noise-canceling, sounds better and is a little more comfortable in the bargain. The Momentum Wireless has little bit more detailed, richer sound. Also, its sound has more immediacy to it, particularly in the vocals (midrange), there's more sparkle in the treble, and the bass is slightly tighter. The MW60 sounds slightly recessed by comparison.
I had home audio editor Ty Pendelbury and Steve Guttenberg, who writes CNET's Audiophiliac column, have a listen. Ty liked the MW60 but preferred the Momentum Wireless, while Steve thought the MW60 sounded "OK." But he doesn't like Bluetooth headphones, so consider that praise.
If you wondering how these sound as a wired headphone (yes, they come with a headphone cord), they sound good -- very similar to the MH40. But there are several wired headphones in this price range (or that cost less) that arguably sound better and offer more transparency, including Audeze's Sine headphone or Oppo's PM-3.
As a headset, the MW60 works well but doesn't have dual mics that reduce ambient noise or allow you to hear your own voice in the headphones.
There are plenty of other premium Bluetooth headphones to choose from. I like the Parrot Zik 3, B&O Beoplay H7, V-Moda Crossfade Wireless, Bose SoundLink Around-Ear Wireless Headphones II and Beats Studio Wireless, to name a few models. As far as sound goes, this MW60 measures up well against those headphones, but it also costs more.
Pricey, but good
In the end, aside from being slightly heavy, the only serious knock against this headphone is that it just costs too much. It sounds excellent for a Bluetooth headphone, but not $550 excellent. But if you can overlook the the fact that it does cost too much, it's beautifully designed and worked flawlessly for me.