My two cents: I don't know any person who is into serious running (I'm into triathlon, so add cycling and swimming) who would spend $350 on the Apple Watch and additionally you are required to have your iPhone with you to use the GPS. A sports watch without GPS, IMHO is a no go at $350. For <$300 I can get GPS, HR, ANT+, waterproof* and +20h battery life. e.g. Garmin Forerunner 910xt.
(I won't comment on the lack of info on battery life and water resistance).
*Edit: changed from water resistant to waterproof.
(I won't comment on the lack of info on battery life and water resistance).
*Edit: changed from water resistant to waterproof.