The finishes are hard to get good photographs of, since they change based on available light. Stainless in particular often comes out looking like matte grey in photos, while at times it looks very similar to the true stainless finish on my P220ST (see the 2nd picture here) The House Black is by far my favorite finish. (again, see my previous post with pictures) It's what Sigs should look like from the factory. I hated the chalky grey Nitron finish of my P229R when I got it.
The ease of cleaning, rust & corrosion protection, and natural lubricity of the finish is excellent. In fact, those were my primary reasons behind refinishing. The fact that the guns look nice is a secondary benefit as far as I'm concerned.