I thought it was a version of "pony" when I saw it in Ocarina of Time, but I respect it a lot more now that I know where it comes from. Very nice name.
Just so everyone knows, this name has absolutely nothing to do with the name Eponine. Eponine is French and Epona is Celtic. I could be wrong; I’m not sure if Victor Hugo really liked the name Epona and just made up a French version for a character. To the best of my knowledge, though, the names are not related.
Epona isn't only named in Zelda. It existed far before in various games and anime. In fact, its first n64 appearance is from a game called Quest 64, where the character was an elderly woman with ridiculous long hair... like a mane.
Although I don't think it's a particularly good name for a person in this day and age, it still remains one of my favorites due in part to my love of horses, and also because it sounds quite lovely.