iFixIt has posted their teardown of the iPod Shuffle 4G rating it a 2 out of 10 for repairability.
iPod Shuffle 4th Generation Repairability: 2 out of 10 (10 is easiest to repair) ● Good: The control pad is attached to the logic board via a connector, allowing it to be easily separated. ● Good: The lack of a screen eliminates a large weak point of other devices, making the Shuffle more resilient to falls. Just don't flush it down the toilet. ● Bad: You essentially have to break it to open it. ● Bad: The battery is soldered to the logic board, making replacement that much more difficult. ● Bad: Apple keeps shrinking connectors. These super-small cable connectors are increasingly difficult to open without breaking them.
You can see a few pics below or hit the link for the entire teardown gallery.