Outside of the solar-charging gimmick, the SmartTalk Solar is a fairly basic Bluetooth speakerphone. It features no voice command, text-to-speech, or audible caller ID of its own. Incoming calls are announced with a cutesy version of Wagner's "Ride of the Valkyries" and answered by tapping the large multifunction button.
Initiating a call must be handled by the paired phone. Fortunately, you can tap the SmartTalk Solar's multifunction button to trigger the handset's native voice dialer (if such a function is supported by the paired phone). Additionally, a double-tap of the multifunction button will redial the last number called.
You can control the volume with the plus and minus buttons and mute a call with the oddly labelled Mode button, but that's about the extent of the SmartTalk Solar's feature set. Call quality is good, with a speaker that's suitably loud and an anti-echo microphone that makes it easier for your call's recipient to understand the words that are coming out of your mouth.
Of course, the lack of A2DP audio streaming precludes the SmartTalk from being used to amplify turn-by-turn directions or driver assistance apps like Vlingo InCar, but those functions are more bonus features than things that we look for in a good Bluetooth speakerphone.
In sum: less is more
The appeal of the Griffin SmartTalk Solar is its simplicity. It doesn't need a voice dialer when your iPhone, Android, or Windows Phone already has a perfectly good dialer. After the initial charge and pairing, you almost never have to touch the SmartTalk Solar other than to tap the multifunction button to answer or initiate a call. The speakerphone turns itself on when you get into the car, it charges itself with the power of the sun so ideally you'll never have to plug it in, and it turns itself back off when your trip ends. How much simpler does it get than that?