Great News! The intro I had written about smartwatches in general and why the Pebble is better than others is gone! Now more Pebble App Development tips!
Developing for Pebble is fun! No, really! It's complicated, but it's fun. It has lots of moving parts, but it's fun!
I am going to skip the part where I tell you why you should develop for Pebble. Because it's fun! And that's all anyone needs to know, really.
The first decision to make is not easy: develop online or on your machine? CloudPebble or local SDK? The good news (more good news!) is that both give you essentially the same results. The difference is mainly one of trust and access. With CloudPebble, you have to have an Internet connection (access) and you have to trust Pebble with your code. With the local SDK, development works on Linux and iOS (not Windows) and you have to trust yourself with the installation.
I chose to go the SDK route, but if you are just trying things out, you should go for CloudPebble. It's much easier, and you can do pretty much the same things there. If you do so, follow the instructions on CloudPebble. If you do the SDK, you'll end up having more control, but will also need to get your hands dirty with the command line. You can, incidentally, still run the SDK if you are a Windows user. You just have to install Linux on your Windows machine, which is really easy. Pebble (and I) suggest that you do so by installing a virtual machine (think VirtualBox) on your Windows computer and run Linux on it.