I'd ignore the 1 star review of this lens as the reviewer completely misses the capabilities of this lens that a zoom won't have. It is fast, both in operation and aperture. And with coverage for an FX format sensor, 14mm is something that would only be a dream awhile back.
now I'm no scientist, and there's a 16mm fisheye, but this is wider but not a fisheye. So what gives? I have a 10.5 DX fisheye, and one of the great features of it was in the Nikon Capture software that you could get for your camera. What the sofware did was take that fishbowl look away and make the photo a rectilinear image by reshaping the perspective.
If that is true, it's probably what makes this lens such a joy to use. Your angle of view is amazing, and the results give you that rectilinear quality, and it's right in the viewfinder. You don't have to wait for post processing to see the results.
It will take a big bite out of your glass budget, but it is an investment that will probably payoff nicely down the road. Of the major investment I've made in Nikon FX format equipment, this is the jewel in the crown.
Drawbacks: yes. #1 The front element is almost spherical and the "shade" wings don't exactly provide superior protection. #2 The lens cover; it's sort of a little leather feed bag looking sack that fits around the shade. It's a bear to get on; and if you're in a hurry, forget it. Maybe it'll get easier over time, but right now it's tough to fit with risking damage to your lens.
Watch the prices, and if an opportunity comes along, grab it.
Kind of like when you buy a car. Once in awhile you sit in a car and know instantly that it fits, and your checkbook jumps out of your pocket. This lens fits.
I'll check back once I get a few hundred more images through this lens, but I doubt it'll say anything other than whatever was already has been said.