Are fisheyes gimmicky or good?

The thing with fish-eyes is that they're hard to use correctly. If you know how to, it's cool, but most people don't. Other than that, it's not so much that it hurts having one and using one every now-and-then, but for us broke skier kids, a fisheye is very hard to justify when there's better/more versatile glass around.

good fisheyes are expensive, and the cheap ones are really terrible optically(for photos), so it's hard to justify buying one as they have such a specific use

weeeellll I suppose that's true if you mean cheap ones are soft.

sharpness is not the only thing that makes a lens good, most of the cheaper ones have very bad CA and color fringing

hasselblad and mamiya both make/made very nice 30ishmm fisheyes that performed wonderfully optically, the canon 8-15L is also quite nice, and for FF use on a budget the canon 15 2.8 is decent. Oh and the nikon 10.5 is decent for a crop body

It's all in how you use them.

Not a huge fan of them in video, I mean I don't really film anymore but I'd say most people that are using them in skiing are just slapping it on and getting the skier in frame. For filming I feel like you really have to get creative with a fisheye. Now for photos, I personally like the look in action sports and you can even make it look right with some portraits and lifestyle shots. But when overused I think it looks gimmicky. That's just the point of view from a filmer turned photog.

It might be just me but I think the 8-15L is stupid