I use my phone when working out, and I love the audio quality of the HTC One. It's great while using earbuds, but the real improvement comes from having two great speakers on the front of the phone. It's fantastic for listening to music, watching videos, and more. They're LOUD - I have a hard time turning the volume up to full blast, and I had to turn the ringtone volume down.
Outside of BoomSound, I feel the same way about the design of the phone as I did on day one; it's gorgeous and I've gotten quite a few "what phone is THAT?" questions since I've been working with it. It's the most beautifully designed Android phone yet, and I expect people to pick it up based on looks alone (though it packs a lot under the hood as well).
Stay tuned for more updates to the HTC One 30 day challenge, and in the meantime, let me know what you want to see @PhoneDog_Aaron!