The speakerphone has two buttons side by side: a green power/call button, and a red end-call/reject-call button (you use the latter to reload the phone book, as well). I found that I had to glance at the device to reach the correct button, as opposed to finding them by feel alone. Like some other Bluetooth speakerphones I tried, the Supertooth 3 lacks a button devoted to the power-on/-off function, and I definitely missed that. I did like the unit's spoken status indicators--"BlueAnt ST3 powering down" or "call ended," for instance. But the eerily robotic voice gave me the creeps sometimes.
The Supertooth 3 gets a big thumbs-up for its phone-book synchronization: Right after you pair the unit with your phone, the Supertooth 3 immediately downloads the contacts. Again, you hear status updates along with a confirmation when the deed is done. After your contacts are loaded into the Supertooth 3's memory, any time a call comes in that it recognizes, it announces the name--a huge plus. What's more, I liked being able to say "Accept" or "Answer" or "Okay" to pick up the call; the Supertooth 3 is the only device on our that lets you answer a call by voice that way.
Your phone needs to support the phone-book sync, though; consult your phone's specifications to see if it supports automatic synchronization. If it doesn't, you can instead send your contacts from your phone manually via Bluetooth. But your phone may not support that function, either--if it doesn't, when a call comes in, you'll hear only an announcement of the number. Nevertheless, you can still dial by voice using your phone's feature. In tests the Supertooth 3 listened well and picked up my commands, although I did have to raise my voice a bit.
Call quality was inconsistent. Some calls sounded fine, with crisp voices, but lots of other calls were laced with interference. A couple of callers grumbled about hearing radio noises in the background--but my radio was not switched on at those times. We heard echoes and crackling sounds, and one caller thought the ambient noise sounded as if it were coming from a churning washing machine. Half the time, the interference wasn't a deterrent, but at other times it made lengthy business calls impossible.
One thing to whine about: The Supertooth 3 has a teensy, blinking blue light when turned on, and that proved very distracting, particularly at night--the pipsqueak of a flash would catch the corner of my eye.