This is a Proof-of-Concept Release of the Pebble Software Development Kit (SDK). Code written using this SDK can negatively impact stability of PebbleOS and in the worst case, brick a watch. As long as you steer clear of poking registers manually and generally setting out to mess too much with the firmware, you should be fine. But we can’t guarantee it at all. The goal with this SDK release is to gather feedback from the Pebble community and funnel that information towards a revised SDK (with memory protection) suitable for wider use. Keep in mind that any code written for this PoC will most likely be broken by API changes between these two releases.
Aside from that, have fun!