Update: This teardown was conducted solely via Interweb, requiring us to defer judgment on a repairability score. Now that we've worked on it ourselves, we can assign it a fair score:

Samsung Galaxy SIII Repairability Score: 8 out of 10 (10 is easiest to repair)

The battery can be replaced without any tools.

Very easy to open and access internal components.

There are only 12 screws in the entire device, all standard Phillips #0 (no proprietary or security sizes).

Smaller components (antennas, vibrator, light sensor) are modular and can be replaced individually, but are adhered to the front panel.

The glass is fused to both the display and the display frame, increasing repair costs.

You'll have to go through the entire phone in order to replace the front panel, since everything is built into the back of it.