The S1 doesn't have the text-to-speech feature of the Supertooth 3, so it won't read out incoming caller ID. However, instead of that, you get multipoint technology that lets you connect up to two different phones at the same time. The S1 will be smart enough to receive the incoming call of whichever phone that rings first. The first phone to be used on the S1 will be designated as the primary phone, though you can swap the primary and secondary phones by pressing the red button for 5 seconds. All calls made with the S1 will be done via the primary phone. We tried this out with both the iPhone 3G and the LG LX370, and it worked beautifully.
Another nice touch to the BlueAnt S1 is the addition of A2DP stereo Bluetooth compatibility. This way we could stream the music on our phones to the S1, which was especially handy with our iPhone 3G with the latest OS 3.0 firmware that added stereo Bluetooth support. The sound quality is a bit tame and probably won't be as good as your car's stereo speakers, but it's a decent option if your car doesn't have an iPod or music player adapter.
Like the Supertooth 3, you can use your voice to answer calls. Simply say "Answer," "OK," "Accept," or "Accept Call" to answer an incoming call. You can only do so if you've turned the voice answer feature on--you enable this by holding down the Volume increase button for 5 seconds. To disable it, hold down the Volume decrease button for 5 seconds. When the voice answer feature is enabled, you'll hear an additional beep whenever there's an incoming call. The BlueAnt S1 will also work with the voice dialing feature on your phone if your phone supports it. But do note that you have to press the red end/reject key to end calls, even with the voice feature enabled.
Other features of the BlueAnt S1 include the ability to pair up to eight devices, last number redial, the ability to transfer calls from the phone to the speakerphone and vice versa, and automatic reconnection. The latter means that the S1, if powered on, will automatically search for your phone and reconnect when you bring the phone back in range.