As I have mentioned in the past, now having a full frame 35mm SLR, I have started to look at a new wide angle to suit.
I have the standard full frame zoom going from 24-70mm, and there are a couple of tempting zooms plus the 24mm PC lens that Nikon make, but these are all pricey.
The 20mm f/1.8 prime gets very good reviews, has little distortion and is a far cheaper and smaller offering to most of the alternatives, I think i’ll have to see if my local camera shot has a copy to test.