My wife out did herself this year for Father's Day. She bought me a Sena Calvary Helmet. It is a half helmet that has a built in Sena Bluetooth system. Got it just in time for a weekend trip so I tried it out. After almost 700 miles and two days of riding and can say that I was impressed. I was able to listen to music, talk to other riders and even answer the phone when my wife called. It was remarkably clear up to about 70mph. At about 80 mph it was not as clear but I don't normally drive that fast anyway.
If you are thinking about a blue tooth half helmet I would definitely recommend it