[Klaus]

With "too extreme" I suppose you're talking about 10mm at FF, right?

Yes. 16mm are the finishing line for landscapes in my book. 18mm or 20mm are still my preference.

If you ask me I'd say that 90% of the photographers can't handle ultrawides and add 9% for those 10mm.

I find it extremely tough to shoot a really good ultra-wide image - and most of our samples in the relevant reviews don't qualify there.

[toni-a]

For me

 

Yes. 16mm are the finishing line for landscapes in my book. 18mm or 20mm are still my preference.

If you ask me I'd say that 90% of the photographers can't handle ultrawides and add 9% for those 10mm.

I find it extremely tough to shoot a really good ultra-wide image - and most of our samples in the relevant reviews don't qualify there.

Agreed here, I am not  an architecture photographer (maybe because I am not good at it) however my trial with architecture says fpr architecture and cityscapes you do need ultrawides maybe 10mm would be enough there. knowing that personally I won't use it and I easily prefer fisheye for such shots, si I  fall between the 9% you were talking about

[chrismiller]

Difficult to use, but stunning when done well!