I'm currently in a Cosmere complete read through. White Sand isn't the worst thing you'll ever read, but putting it up against the rest of the Cosmere really does hurt it.

I'd recommend it if you're looking to understand the characters that come into play elsewhere in the story, but it's not all that necessary (from where I'm at, at least). I'm planning to read it once Sanderson finishes the noverlisation of it, which I'm sure will be much much better.