While I haven't tested it underwater, it's small but easy to read, even using the side viewfinder. It readily takes in light to make the display better in the dark. It's simple to use, so the fact that the instructions are only in Chinese isn't a problem. The delivery happened much sooner than I thought it would.

The product is satisfactory, however, its size is slightly smaller than expected.

100% compatibility. Now we need to test how the compass will behave underwater :P