We didn't exactly have 40 hours here to test the audio playback claims (in fact, we didn't even have eight to test the claims on video), but you can bet that'll be a huge selling point.
We didn't have much time to compare music playback with other phones, but audio quality with various headphones and earbuds was up to our higher-than-average standards.
This is very disappointing because this bug effectively makes everything we like about the Echo a moot point, as without rock solid 1080i playback, we couldn't recommend this device to anyone.