Great as a lightweight travel ultra-wideangle lens.
And you're right the Nikon 16mm FE is too ex. I was deciding between the 2 and chose the Sigma because of reviews that said that the Sigma is as sharp if not sharper than the Nikon. I had to give up full compatability with Capture NX2 but the Sigma worked out fine with Capture NX2 in the end.
Was this Mathilda's 8:15 PM slot? I caught the earlier one.
Here's more Peleng 8mm goodness. These are all on a 1D MkII. If you don't mind manual focus, it's a nice lens to have. I rented it, but personally, I wouldn't buy it. I'd under-utilise it.