Efficient

It does what it is expected to do: changing a string on a site is as easy as choosing WordPress / a plugin / a theme (might be the hardest part…), typing part of the string in the search box, and editing it. Then save, and the corresponding file is automatically compiled and used.
You can get the translation file, the source or the compiled one, which eases transfert between sites.
The only thing missing is a quick way (shortcut key) to go back and forth between the translation list and the traduction area: Tab goes from the first to the second, but I see no simple way to go back to the list and translate the next string (or skip some, etc.).