My quick review.
I just picked it up today. Mine says 646 by the way.
I really wanted to love this thing. I'm a huge fan of HD Radio and own 3 radios before this.
I was very close to picking up the ZuneHD just to have a portable option.
First, the app is very basic.
Tuning is very touchy. Press it a certain way and it will go back to your last tuned station.
The reception, as I feared, is horrible. Driving around in my car, using the AUX input, I was barely able to pick up what I thought would be a strong HD channel.
I wasn't blown away from the audio quality but that may have been an issue of reception.
Another huge issue I had (and why I passed on the ZuneHD) was no AM support.
90% of my HD Radio listening is AM sportstalk.
Why is AM dismissed in these devices? It uses the same chip, same spectrum (I assume) and is advertised by HD Radio as a feature.
Even this device mentions how HD Radio improves AM, but as of now, FM only.
I was able to get it for ~ $45 with the coupon and have no idea how they think they can charge $90 standard for this.