Yesterday was my first full day, using the Smartband Talk. I actually made one call and received one call on the Smartband too, and when I came home from work in the evening, the Smartband's battery was still around 70% which impressed me (considering I'd made calls on it).
Well, I actually expected my phone's battery to be drained more than usual. I don't usually have Bluetooth and NFC turned-on permanently. But the battery on my HTC One was still nearly 80%. Usually, when I get home from work, the battery is less than 50%. I definitely handled the phone a lot less yesterday. It's an HTC One M7.
So, I'm happy.
The Smartband functions are a little limited. The voice recognition isn't the best - being able to launch "OK Google" would be so much better. But overall I'm happy.