What's interesting is that if you think of the Watch in terms of it being a computing platform, 12 million devices shipped might be considered a bad sign.
Sega had two back-to-back systems that shipped in that League (the Saturn shipped 9.26 million and Dreamcast shipped 9.13 million) and both systems are considered massive commercial failures, so bad that they nearly sunk the company forcing Sega to pull entirely out of the hardware market.