As far as Horse Archery goes it certanly feels different but I whont say nerfed to the ground yet. Yes the aim is ridiculasly bad when moving and yes the uppkeep of arrows that break every round is digging a steep hole in my wallet but you can still be successful.
Cav: Not as good manuever as before but thats the same for all cav. I can still avoid the other cav, infact its much easier now when lancers cant stab to the sides. This also means I can go closer to them to shoot so dehorsing is pretty much the same. All in all it felt easier to fight cav.
Inf: Bump-shot is harder but if you hold the shot untill you stopped the horse after the bump its still as effective. Bad thing to do if the bumped guy got a friend near by though, and I bet both poke and slash retaliation will be easier since you dont need to fear an arrow before the bump as much. All in all against inf you are a little weaker but so far I didnt notice a huge difference. You have to decide if you are gonna stay away and shoot or ride over them and shoot.
Archers: It felt like I did more dmg with my shots but im not sure of that. However I have a disadvantage against an archer midrange since I cant move and shoot (hit) and I cant dodge arrows like before. Long range is the same as you normaly would stand still there while firing anyway. Short range feels more or less the same too, though I got to admit I bump more and shoot less now. All in all fights against archers is harder but imho not unfair.
Now this is only from ~1h testing and throwing hasent been widly used yet so I might change my opinion. The only thing I find sad though is that you are no real Horse Archer anymore, you are an archer on horse as you stop, shoot, move and repeat. Feel sorry for all the lancers out there and I agree with Jailbait.