I'm satisfied with what we have now that it's more than enough. You can't interact with objects when mounted, yet saw that it'll be changed later that I'm fine with this for 'now'. For now it's fine, yet during travels it helps when you can type to someone without stopping, among other things. My major issue with horses is that they need some sort of 'auto-run' similar to 'Skyrim' & 'Mound & Blade: Warband' where the former you press the 'V' button to toggle such while the latter you simply tap W or S to toggle pace up and down. Love how it 'feels' when you ride a horse in the walking pace.

However curious if they should jump slightly higher or if that height is intentional. Love how weighted horses weigh in game that they can also jump.

12 & 12, but it's 24 for simplicity sake. Same with how you can add the 24 slot saddle bag to carry additional cargo with you, something Minecraft now needs to learn from. Saddles being slapped onto the horses is a nice touch. (Someone noted this and I agree with them) Horses 'whine' too much/too frequently, yet have neat sounds otherwise. I love how fast they are, and even faster when you hold shift to make them run. Waiting to play survival where the real fun shall begin, yet these are just my 'quick thoughts'. I had to try it in creative mode just to see how these horses handle, and I love them.