If you were to compare them to cars, the BlueAnt S4 would be a Lincoln Town Car, and the BlueAnt S3 would be a Ford Focus. That doesn't mean the S3 isn't a good speakerphone, but it's just not as fancy as its big brother. It lacks a lot of the S4's higher-end features, it's smaller in size, but it is cheaper and easier to use.
If you squeezed the BlueAnt S4 down to a rounder shape, you would end up with the BlueAnt S3. The S3 measures 4.17 inches long by 2.71 inches wide by 0.78 inch thick, which is just a smidge shorter than the S4, but is a touch wider and thicker. Though it doesn't differ much in size, it's definitely not as sleek in appearance. While the S4 is clad in glossy black and brushed metal, the S3 has a simple all-black plastic shell instead. With its rounded sides and matte surface, it's a much more modest gadget in appearance.
On the front of the device is a large speaker where the BlueAnt logo sits. Directly above that is the front panel that houses all the controls. They consist of the multifunction button and the volume controls. If the buttons don't feel like you're pressing them, it's because they are all touch-sensitive. Simply tap the multifunction button to perform a variety of tasks like answering calls or pairing another phone. For the volume controls, you have to slide your finger across to adjust the volume. When the speakerphone is attached to the visor, these controls should face toward you. Next to the volume minus sign is an LED indicator.
We adjusted well to the touch controls, but we can see how some people might prefer to have physical buttons, especially when you're driving.
The S3 comes with two visor clips, each of which slides on to the back. One of the clips is for narrow sun visors, while the other is meant for slightly thicker ones. On one side of the speakerphone is a simple sliding power switch plus a Micro-USB charging port.
The BlueAnt S3 comes with a 12-volt USB car charger, a Micro-USB cable, and a user manual.
The BlueAnt S3 does not have the same voice features as the S4, so you can't say "BlueAnt speak to me" to trigger the speakerphone. However, you can perform a few tasks with your voice. You can answer calls by saying "Answer" and ignore them by saying "Ignore." To engage the voice command functions of your phone, you need to press the multifunction button first. This won't work if your phone doesn't support voice dialing.