[snogglethorpe]

I'm sort of curious as to why it's so big ... given its very modest requirements.

Is it just the desire to avoid expensive proprietary highly-integrated components?

[I work for a cellphone company, and my boss used to carry around a complete cellphone CPU+RAM+Flash+driver-chips board around in his wallet... it was about the size of a postage stamp (this is about 12 years ago, for "medium power" cellphones). Battery / display / keyboard / I/O ports / antenna etc, took up the rest of the interior of a real cellphone, but it seems that this watch is explicitly designed to be very low-power, etc, and avoids many of the other requirements in a cellphone...]