Mmmmm, love, Love, LOVE sushi.
THere are different types, and often (not always) beginners do better with some types than others.
Nigiri (my favorite) is usually a piece of fish/meat/something on some rice (often/usually with a tiny smear of wasabi under the fish). It's often/usually raw fish but not always (unagi and anago are not raw, shrimp is usually cooked, but is sometimes raw, etc...)
THere are hand rolls (temaki) which are usually very similar to regular rolls but have more nori (seaweed) than a regular roll.
Then there are the rolls that most folks think of when they think of sushi. There are some traditional rolls, and then most rolls are not traditional.
pretty traditional is a tiny cucumber roll or similar tuna roll. They are usually very small.
then there are the larger rolls that most folks are familiar with. They usually have a bunch of ingredients. Traditionally, the nori/seaweed is on the outside, but these days, it may be on the inside. Many of these are easier for beginners to start with because they may or may not have raw fish, but if they do, there are enough other ingredients that the taste/texture of the raw fish doesn't stand out as much.
I like all sorts of sushi, but I prefer nigiri and hand rolls.
A good roll for most folks to start with is the California roll. It's made with crab meat (well, most of the time it's made with artificial crab meat).
Personally, I avoid sushi at Chinese restaurants, especially buffets. I'm sure there are probably some places that make decent sushi that way, but I'm not eating raw seafood from anywhere that the primary goal is cheap food.
Good pizza and bad pizza are still generally reasonably tasty and good. Good sushi is amazing. Bad sushi is at best, not tasty, at worst may make you sick.
I have had amazing sushi which has ruined mediocre sushi for me. I will still upon occasion eat grocery store sushi, but I avoid anything in a grocery store with raw fish.
Unagi is one of my favorites. It's grilled eel with a thick sweet and salty sauce drizzled over it. The meat is very soft and practically buttery.
As far as the raw fishes, popular are salmon, tuna, yellowtail, and albacore tuna. Those all have a very mild flavor. Tuna is my least favorite until you get into the premium tunas chu-toro and o-toro. O-toro is like the wagyu of the tuna world, it's fatty, buttery, and tender. chu-toro is like a good ribeye, it's in between the regular tuna and the fatty tuna. And then regular tuna is not fatty.
Mackerel (saba) is a silver skinned, oily fish with a much more pungent flavor, and is one of my favorites.
uni is sea urchin gonads/roe. It's generally considered a delicacy. I've had it several times. When it's good, it's really good. When it's not, I am not a fan. The taste and texture seems to vary quite a bit.
When I'm looking at raw fish nigiri, I'm expecting the fish to be smooth, usually shiny, and holding together. The only time I am likely to be OK with the meat looking like it's falling apart is if it's something with fat veins and the fat is falling apart, but the meat should still look good. I don't apply the same criteria to cooked fish.
