iFixit recently performed a teardown of the Pebble Smartwatch and ultimately declared it unrepairable. The teardown specialists found copious amounts of adhesive inside the watch used to keep water out (a good thing) but it's this very adhesive that also safeguards against human interaction.
While the team was able to eventually get inside the smartwatch, they weren't able to do so without compromising the e-paper driven display. Once the display has been removed, however, it's generally smooth sailing the rest of the way.
Inside is a single small ribbon cable that houses four buttons, three LEDs and a Bluetooth 2.1 antenna. As such, replacing an individual component will be impossible even if you could manage to get the display off without breaking it.
Behind the backlight guide panel is the motherboard / battery / vibrator assembly. The assembly is held together by what iFixit describes as very delicate soldering. Again if any single component here breaks, the entire assembly will need to be replaced.
The team found an ARM Cortex-M3 MCU with a maximum speed of 120MHz, an STMicroelectronics LIS3DH 3-axis accelerometer and 32MB of Micron flash on the front of mainboard. The reverse is home to the system's Bluetooth controller chip from Panasonic. The system's battery from Fullriver is rated at 3.7v and 130mAh. Pebble claims it can last for more than seven days on a single charge.
iFixit uncharacteristically didn't award the Pebble Smartwatch a repairability score but instead, listed a few of their repairability and durability findings. The team said low power consumption decreases the frequency of charges which will increase the battery life. They also liked the easily replaceable watch band but the inaccessibility of the battery would limit the device's life to no more than 10 years. Furthermore, it's impossible to open the device without destroying it or at the very least, compromising the waterproofing.