That's tough to say without having tasted it myself and without knowing what kind of restaurant you got it from. Obviously, production-line sushi like at a hospital restaurant isn't going to very good. I don't know if other places are like this, but where I live sushi is so popular that pretty much every Asian takeaway restaurant sells sushi, even if the cooks have a Thai or Chinese culinary background, which can also lead to varying quality. I had to go to a couple of sushi bars before finding one that made good sushi.
I personally wouldn't describe well-cooked sushi rice as gummy or difficult to swallow, it should be fluffy and have a firm bite, but I guess that might depend on your palate. Also, sushi is a full meal so you should feel full after some nigiri and maki.