Personally, I think they are great for widefield (whole constellation) views from dark sites. They come into their own when you look at the milky way towards the galactic centre. You need to get used to using them, but I am quite taken with them. However, they are no substitute for “conventional” binos.
I have a pair that I used down on La Palma and here in the UK. They are very nice, at least the Vixen ones, and give interesting wide field views. I would say that they may not help too much from light polluted skies but form dark skies they are very interesting. I suspect the other ones (Kasai and other branded versions) are Chinese clones, hence the cost differential. They do have their uses but I suspect that they maybe a limited use piece of equipment.
I bought a pair for low power views of constellations and they give a big boost to your vision by adding 1.5 mags without changing the size that much- it’s like having super-eyes.
They are simple Galilean design and there is some astigmatism and the quality falls off noticeably away from the centre but they are fun in a dark location, especially for sweeping the Milky Way and looking at large clusters like Pleiades, Hyades etc,
I have the Vixen 2.1 excellent BUT you need 2 things good skies and good vision they are not suitable with a spectacle prescription of for example +6.75. They are best used without specs but are adjustable to about +/- 5. The manufacturers don’t bother to tell you !