My son works there, I have tasted them. they are indistinguishable from a meat burger. Very good but currently about one dollar more than a meat burger. Most places that sell impossible burgers allow the customer to order a regular burger and then substitute the Impossible burger in place of the meat product which they also sell.
I am pleased that the product meets kosher standards and is not meat. So it can be eaten with meat or dairy. This expands the sales potential. I believe the same goes for food that meets the Muslim requirements. Impossible foods can sell everything they produce.
Though I've never tried one, I've heard the same thing.
I still wouldn't call it "The World’s First Kosher Cheeseburger." If we're going to use "-burger" only for genuine meat products (perhaps allowing the most obvious exceptions, like "veggieburger"), the Impossible Burger wouldn't count. If we are going to use "-burger" more freely for foods that aren't meat, the Impossible Burger isn't the first. It may be the closest simulation of meat so far, but I'd use a less misleading description. I don't like the food equivalent of clickbait.
I've also heard of, and heard objections about, "kosher cheeseburgers" made with meat and pareve soy cheese. For example, from 2008,
“Jewish law is very concerned for appearances,” said Rabbi Basil Herring, the executive vice president of the Rabbinical Council of America. “Not only should you always do the right thing, but it should be seen as the right thing.“Any Jew who keeps kosher knows a cheeseburger is not permissible. But . . . what happens if a young kid, a 10-year-old, goes in there and says, hmm, maybe cheese on a burger is OK?”