Sadly in this particular case a wip wouldn't have helped as the issue lies mostly in the colouring (or rather, the lack of proper colouring).
I do now avoid commissioning anything above a certain price range unless there's a wip stage. Though that doesn't help if the problem is with the colouring stage like with this one. While hopefully I won't have the same situation again; if it does happen I can have a bit more confidence in saying if something falls noticeably short of the artists usual work/commission example.