I've played a few Harvest Moon games and I must say that I do enjoy them quite a bit. I only have, like, a few from the main series--Harvest Moon DS, Harvest Moon: Island of Happiness, Harvest Moon: Tree of Tranquility, and I got A Wonderful Life for Christmas last year. Um, I think I enjoy playing the Rune Factory spin-offs a bit more, though. They're almost like a mix between Harvest Moon and Legend of Zelda... well, sort of. I actually have all of those--except Rune Factory Oceans, which I don't even think is released in North America, yet.
If you want a bit of 'story time', then read the following paragraph:
I remember the first reason I ever purchased my first Harvest Moon game--Harvest Moon DS--was because it was a game that had my favorite animal, sheep, in it. I remember I got my first sheep in that file in Summer 27, if I can remember correctly and went through a rough Winter in fear that my fodder barn would collapse. xD Then in year 5 (by this time, I had a stone barn), I was very picky on when to save because Tina (that was my sheep's name) was due to die and I kept on resetting to avoid that. One day, it became unavoidable, so I saved--but then quickly changed my mind about it, so I shut off the power. And, well, the game got erased... I only had rescued about maybe 60 Harvest Sprites, but I was devastated... So, I started a new file, named my character, dog, cat, and farm the same thing--and once again got Tina on the same day, with the fodder barn and put it in the same spot for the first Winter until I got enough material stone for a new barn. So... that's quite a story... (Moral: never turn the power off when a game is saving... the warnings don't lie!)