In my opinion when I first tried horse meat it tasted to me like a mix between beef and venison.
Venison is deer meat so if you had ever tasted deer meat then that's what it seems to taste like along with beef.
I haven't had the chance to eat horse meat anymore since it's not available here and I only ate it with a friend who slaughtered a horse for the meat.
It was actually pretty good and it also makes good meat to put in Chilli and Stews.
Horse meat is also denser and sweeter in taste than other red meats.