I worked for t-mobile for 5 years (but have been out for just over a year, so some of my info may be out of date), and I worked a lot with bluetooth
Definitely the biggest pro is the handsfree talking. In many states police officers can pull you over for talking on your cell phone, so this will protect you from that. There are also many styles...some are just like earbuds that tuck in your ear, some have clasps that go around your ear, some even can connect to a headband-type structure.
Some of the downsides is that the initial sync between the bluetooth device and the phone/car can be tricky. The sync process isn't the same on all devices, and sometimes car manufacturers have certain ways you have to sync it and the bluetooth has certain things and it's like a song and dance to get it connected. It's also not uncommon to have the pairing get "lost", where you have to do the initial sync over again occasionally. It's important to really read the instructions, both for the bluetooth device, but also for the device you are connecting it to. If you don't have the original paperwork/manuals, a google search will usually pull up basic instructions and most likely a youtube video
Some manufacturers I've worked with are Jawbone, Samsung, Motorola and Plantronics. I've never personally used a Jawbone, but the customers I worked with always loved theirs. I really liked the quality of Samsung's products, but I found Motorola to have more information/help available on their website (including a walkthrough on how to sync, with pictures of each step), and the quality of Motorola's bluetooth devices on on par with Samsung. Plantronics were decent, I haven't used them in a while to see how the quality is. They didn't have anything that stood out from the others at the time I did use them, so my feelings on their products were "meh" at best.
Like I said, it's been a bit since I've worked with any of these products, so take the info with a grain of salt
Hope it helps!
Started Weight Watchers May 5th, 2013
Started MyFitnessPal June 23, 2013
"Rather than aiming for being perfect, just aim to be little bit better today than you were yesterday"
A Gamer's Journey of Weight Loss
First goal: 210 lbs-5% of body weight-achieved 6/24/13
Second goal: 199 lbs-10% of body weight and ONEderland!-achieved 8/20/13
Third goal: 175 lbs-high school graduation weight!