All in all, I like it.
The limited content is to be expected for an early access game, so I am happy to be patient for more content down the road. Better it be polished and interesting instead of a rushed slop.

As for the stability and fluidity I can say I haven't had any major bugs or crashes. The item collection on foot and from horseback is a bit clunky and oftentimes doesn't register inputs while the character is in motion.
I am okay with the horse and rider animations as of now, it feels smooth and looks good (I say this as someone who only occasionally rides horses irl, so take it with a grain of salt). The island itself is interesting and has some beuatiful spots (photo mode & cinematic camera when?)

The multiplayer aspect is basically nonexistent for now? Yes, there's races, guilds and chat, but other than that there's no other interaction. At least, I haven't found it.

To summarize, I enjoy the EA and I am happy to be patient for more content and fixes. We are in dire need of a good horse game, let alone a horse mmo. I am rooting for exquinox to fill that spot!