It is a weird thing reading about it as there is a lust to have such a thing but to be honest would probably never use it more than once or twice and a smart phone is more flexible in either case... plus that it is going to be kind of expensive (450 as early bird on Kickstarter) which really kills any lust for a big watch mini synthesizer.
But there is something funky to it anyway and it would for sure work as a conversation starter and a lot of people would think you must be an annoying hipster idiot!
To check out the Kickstarter:
www.kickstarter.com/projects/synthwatch/audioweld-synthwatch-worlds-first-wristwatch-synth?ref=nav_search&result=project&term=synthwatch