Summary: I replaced a Plantronics M155 with the Plantronics Voyager after having poor bluetooth headset performance issues on phone calls (over cellular or wireless access points). No improvement. It is either the iPhone 5s, or local wireless interference. I hoped the improved tech of the Legend would help. It has not.
Excerpt: I bought this headset having used many plantronics in the past. Was satisfied with the quality of the headset and the sound was really good. People couldn't hear anything but me on the other end. Wasn't too fond of the charging port which is a magnetic fitting not a micro usb. About 45 days after owning the product it quit charging. From reading other reviews on the internet this is quite a common issue with this kind of charger.
Summary: I have both a 5 and 5s. I have two of these headsets and the charging case. Both headsets are pairs to both phones and one is in the charging case so I am never without my headset. When they are working well, they sound good and last a long time. The charging case ensures my headset is never dead and at least the case takes a micro USB to charge it. Often times though I get poor call quality if the headset is in my left ear and the phone is on my right side belt.
Summary: Tired of my colleagues complaining about the terrible voice quality they would hear when using my iPhone headset, I decided to shell out the $100 for the Voyager bluetooth headset. Unfortunately the voice quality (what the listener on the other end hears) is not very good. I get people saying I sound robotic and digitized.
Summary: Just got mine via company issue. Initially features look nice, but the singular most important killer app for me is the old Voyager Pro's ability to access the iPhone's built in voice recognition with the press of the earpiece button, and say "Call the office" (all without any configuration).