I have a pair of goats for my horse [a pair so they panic less when I ride my horse - they still panic a little but not nearly as much as I'm sure they would if I were leaving a single goat behind! haha] and it's seriously the best.
In September, it'll be a year of them being here and I still have no complaints. The older goat [one is 10, the other is just about a year and a half] is really laid back, great with kids, and just all around nice to be around, BUT she's afraid of my horse. She'll be near my horse sometimes but they don't really have a "connection."
The younger guy is more sassy, more excitable, but smart as all get out [I've been training him to do tricks] and deeply bonded with my horse. My horse really enjoys mutually grooming him and they are rarely apart.
The younger guy does have a penchant for slipping through fences into the next pasture over, but he never actually leaves the pasture altogether and he always returns to "his" pasture on his own or when I call him. The older girl escaped once when I forgot to check her water and the younger guy had tossed it earlier in the day [she's too short to reach the normal trough, the younger guy is about as tall as/taller (39 inches, as of a few months ago) than a large mini so he uses a normal trough]. She had put herself back in by the time I arrived to put her in and she hasn't tried to escape since.
They do have a solid 6+ acres of varying terrain to explore/graze which probably helps keep them entertained.
Anyway, I LOVE my goats. They are way less stress than having another horse, they are super loving, most of their care can be done at home [hoof trimming, etc, is SUPER easy for the owner to do], and they don't eat a whole lot.
My old girl goat is a bit of a 'hard keeper' and actually probably eats more than my mare does, but that's due to the goats' age and the fact that my mare is the world's easiest keeper!
They are super rewarding and really fun. I even take my young goat on hikes and I've been teaching him to pony off my mare. Super super fun.