The Apple Watch series 3 reviews are starting to show up online. My favorites were from John Gruber and 9to5 Mac. There also appears to be some sort of bug with unauthenticated Wi-Fi networks but I expect that will get sorted out.
While Apple’s marketing is focused on the fact that the cellular Apple Watch makes telephone calls, I think the more relevant point for nerds is the always on Internet connection. Having your watch be able to use Siri, connect to the Internet, and otherwise interact with the world without having to first go through the middleman of your iPhone seems to be a significant benefit. All of this said, the cellular companies charging $120 a year for the connection seems pretty steep.