I'm a heavy user of smartphone headsets, and my current favorite up to now was the Plantronics Legend. It has massive battery life and a ton of sensors, and it was the best headset in noisy environments. I say "was" because Plantronics just upped the bar a lot with its new Voyager 5200.
While it looks almost identical to the Legend, the Voyager 5200 raises the bar with respect to the amount of external noise it can mute. At $119, it is one of the most expensive headsets in the market, but for folks who live off their phones, like me, it is money well spent.
Modifications include more microphones, a more aerodynamic design (to reduce wind noise), and even more sensors. In use, the product does a far better job of cutting down wind noise (I tend to drive convertibles). Coupled with its optional charging case, it should last for a week or more of normal use before you have to plug it into the wall again to charge.
Controls have been simplified. It now has a visual cue that it is on mute, and it will remind you if you try to talk while it is muted. It will answer a call automatically if you pick it up, and it will attach to your computer with an optional dongle if you want to use it for Skype calls.
The Plantronics Voyager 5200 is my new favorite smartphone headset, and it's my product of the week. (I don't go anywhere without it.)