I have the HS820/V551 combo and for the most part it works great. In addition to the ringtone problem PNG already mentioned I have the following dislikes:
- The fit is loose for my ear. It falls off if I turn my head quickly.
- It doesn't come with a lanyard so you have to carry it in your pocket. See next point.
- If you accidentally tap the main button while it's in your pocket it will do a voice dial without you knowing it. Many times my wife calls me on the office line to tell me to hang up the cell phone because she listened to me get out of the car and walk up to the office. Last week she listened in on a coversation I was having with a lady I met at the tire shop while I was getting my winter tires mounted. Good thing I was a good boy that day.
I've been trying to find a lanyard for it but no luck. I know the previous models came with a lanyard but I've yet to see it for sale.