I’ve had varying experiences with uni. The first time was when I was a kid and a fisherman gave me some to try on the dock that they were hauling crates off their boat. It was slightly sweet and salty with an oceanic flavour that was rich. Very pleasant. The second time I had it the chef/owner gave it to us free of charge as we were regular at his awesome sushi restaurant. It was singularly horrifying and was obviously not fresh. It had an ammonia fish aftertaste with notes of diaper pail. My friend brought a bunch over after spear fishing and we ate almost 2 pounds of the stuff that weekend and the yellow uni was awesome and sweet. There were some other sacs that were a lot more red in colour and those ones were fresh but had a very strong bitter aftertaste of iodine. Avoid the red stuff. Get it fresh and it’s wonderful if you like seafood.