Whoohoo,
I like that Idea of an self programmable Watch with bluetooth (and its the better with an arm core)!

And if they increase the running time on one charge, I think I would buy one!
(4 days is way to less, I would constantly have to ask other people for the time, because I would forget to charge that watch.
Even my Mobile Phone lasts nearly 2 Weeks on one charge ...)

I hope they will improve that.
How about using an e-Ink display or Mirasol display or the like
and an MSP430 or an ARM Cortex-M processor to save some energy ...

sorry but i call hardly believe your phone lasting 2 weeks on a charge.... what do you use? and the 4 days isnt bad... been using this since day one and every night when charging the BB, the watch gets a charge... not an issue at all... do you expect a bluetooth headset to get 4 days of usage all the time? no, think of this as the same... it takes about an hour for a full charge so thats fast

yeah, 2 weeks for a phone to last is very unlikely if it's a modern smartphone, BB's have probably the best battery life and with light usage I can get 3 and a half days out of my bb torch. Heavy usage (300+ emails, 100+ bbm's, 50 mins of calls, wifi, bluetooth, twitter etc) and I get about 80% drain on my battery in about 40 hours.

I've got an inpulse watch, and as the updates have rolled out thick and fast from the Allerta guys, the battery life has constantly improved. Mine started with about 28 to 32 hours of life, now i'm regularly getting 38 to 42 hours of life on the watch with that heavy usage from my BB.

30 to 40 minutes charge seems to work best for my watch, any more than this and I tend to find the battery life is at the lower end of that range