My Day is about 35 years old. Never had a problem with it. Most of those years it was not irrigated. Now it's in a drip irrigated zone. No disease or bug problems. Virtually no fertilizer either.
Production was very low in the early years. I just didn't pay any attention to it. About half of the tree was wrecked by hurricane Wilma. It bounced back fine.
Fruit season is generally from late July through August and part of September (in Boca Raton). This year was less than the previous several years - maybe 70-80 avocados. Average weight about 1 pound, I would say. In some prior years we've had hundreds - maybe 300-400.
The seed is pretty big. The skin is smooth and shiny. Green during development, then starts to change to a beautiful shiny black. Convenient, because you know those turning black are ready to pick - no guesswork. They ripen from hard to soft and edible about 3 days - skin goes all black and goes duller. The seed pops free and rarely leaves the seed husk sticking to the fruit. The only trouble they give - and it's not a lot of trouble - comes in scooping the fruit away from the skin. Hass avocados have that hard, stiff skin and it's so easy to just run a spoon inside and zip zip, it's done. The Day skin is very soft and thin. It's easy to tear through the skin so you have to work it with a bit of care.
The taste is excellent. Very creamy texture, golden color, can be spread like butter. All in all it's a fine little avocado.