*I* also don't understand all the nagging on this fabulous lense. A rectangular native 11mm f4 prime on full frame would be a smasher.
The old 13mm of Nikon is a rare lense, costs a fortune, is tripple the size and even only @f5.6 (google!). And here we get even a Zoom
... for 3 grands.
If you can't afford, don't buy it. On Leica you pay more for a primitive 50mm f2.8 standard. And no ones cares.
Then we read a lot of cheap APS-C lenses (EF-S 10-18) which is nothing even close to a full frame lense and even if we compare it to fullframe it would be a 16mm, only. I think this lens will be worth every cent, for people knowing what to do with it... an no, landscapes are not the meaning of a wide angle lens (http://www.kenrockwell.com/tech/how-to-use-ultra-wide-lenses.htm
Maybe the lense even has a filter-slot on the lensback... so this is also a nice feature which I miss on my 14mm 2.8(no Canon-L). This would help a lot of people using Infrared, grey or coloured filters in the field. And to the IS-wanting crowd... I don't think that it's needed to implement an IS into a 11mm lens, because, if you can't handhold 1/10th of a second you should have more serious problems otherwise. The IS would also be useless on moving subject and if I think about the optical formula, the lenselements in the IS-Group is maybe something around 5-10 mm in diameter. Nice try to get this small piece precicely controlled in small angles.
When I now think how they managed it to get it to work on a 44mm focal flange, than I have respect to the ingeneering of it. I'm honestly waiting for the first examples...