It's arriving a few days later than originally anticipated, but the first big Apple Watch software upgrade is here. watchOS 2 lets third-party developers create apps that run directly on the device itself, without relying on a connected phone. That means the apps have access to sensors embedded within the Watch itself, and they should run faster and be easier to interact with. Some have compared this change to the introduction of the App Store on iOS in 2008, but we'll have to see what developers use it for first. Other changes include new customizable Watch faces with Photo, Photo Album and Time-Lapse, plus upgraded Apple Pay and Siri integration. It also has Activation Lock, so if someone steals your Watch they can't just reset it or easily access your data. One thing you'll still need your iPhone for is to actually get the update -- owners can check Software Update under the Watch app to start the download now.