???
It grants auto success on Command an Animal checks. You don't even need to roll such checks when commanding your animal companion, so the Ride feat does absolutely nothing for them.
Yes, Ride is a strange feat during the major part of the game. Because if you have a horse for example (buying one) without the AC feat its basically stays level 1 forever. Basically turning into a very high risk to use them in a non-lvl 1 encounter.
Maybe can be useful outside the encounter mode yet if you are riding a domesticated mount like a horse your degree of success is already increased by one step and you probably not even need to check and I believe that most GMs simply ignores the Command an Animal checks in exploration mode.
It's basically an almost useless feat with some very few exceptions.
I don't know of any way for an Animal Companion to take a feat. But Ride wouldn't be my top pick. Most would look really strange when riding a horse.
How not Farien? Don't you never think about to take a ride in another creature?
Personally I don't really like being carried. Though not nearly as much as I hate being put in a Pet Cache all day.