The latest firmware update for Pebble's various wearables is going out today. To install version 3.9 on your smartwatch, your Pebble app for iOS or Android needs to be up to date first (the required iterations are 3.6 for iPhone and 3.9 for Android).
The newest firmware brings with it an API for the Pebble Health step and sleep tracker, which means developers are now able to use those stats for apps and watch faces. Health-enabled watch faces will show up in the Pebble appstore soon. Speaking of Pebble Health, this now allows you to show step distance in kilometers and not miles. It's also more accurate overall.
If you use an iPhone, you can send custom responses to received messages through your Pebble smartwatch. As shown above, you set up your canned messages using the Pebble app for iOS first, then you'll be able to choose from those options once your wearable notifies you of a new message.
If your handset runs Android, you can reply to incoming calls with a text message. Instead of answering a call, you send a voice note, emoji, or a custom message. And with the Send Text app for Android you can even start conversations from your Pebble. MMS notifications have descriptive icons from this point on, and they show any text that's included.
Finally, the Watch-Only Mode which kicks in when your Pebble's battery is low now has a new look and gives you more time to find your smartwatch's charger.