Well, I didn't find any decent samples from Ʃ20mm f/1.8 when I was looking for something really wide and the reviews weren't very promising either. So I just skipped it and grabbed a Samyang 14/2.8UMC. However, I was considering the 12-24mm DG HSM zoom too, but Sigma's QC was awful back then. Crazy copy variation lottery wasn't very tempting, rather scary. Maybe Art version of 12-24mm is more realistic and reasonable expectation. The new(ish) Sigma 8-16mm DC HSM is very good.
And yeah, that macro feature is a very nice and unique selling point. I hope Sigma will include it in their next 24mm.
That feature alone make the 20mm Sigma a lens worth having IMHO. I consider it one of my specialty/fun lenses that may not win any technical awards but it sure is a great creative tool if used wisely.
I've attached two samples shot with this lens that show its capabilities. Both shot with a 5D MkII.
Nice shots. But when I look closely I see f/8, the uniqueness is lost and the 20mm doesn't have that feature, or does it? I think it is 1:4+ at MFD, similar to many other wide angle lenses like 17-40L.