Just in case people are wondering, nothing but the main software (13.22 -> 13.23) has changed... GPS, OHR, firstbeat software, all the same version as 13.22.
So with a fix for an app I've never even heard of, one of the least impressive firmware updates ever I'd say, heh...
*Edit*
Might be a coincidence but since installing the firmware (fully charged) my watch still says 100% battery... This is almost 19 hours now. I know the first few hours are iffy, but don't think I ever saw this (and no, I don't think the firmware improves the battery that much ;) )
Connected it to the charger and rebooted it but for now still at 100%, will see how it goes...