I finally put some time into Hyrule Warriors last night when my brother stopped by. A few thoughts:
I'll probably never play this game alone. It didn't seem fun enough to do so. As a co-op game, it's pretty good. Not great, but definitely not bad.
The camera is pretty awful. Centering the camera behind your character works in regular Zelda games because they're typically pretty slow. An action game as fast as Hyrule Warriors could stand to have a much smarter camera. The only thing preventing this from being stupidly annoying is the fact that thus far, the enemies don't really do much.
The game moves so fast at times, causing the camera to "bounce" (particularly when running) that it creates the same problem I have with first person shooters. I get that headache where it hurts behind my eyes. The difference is that once I stop and start slashing at enemies, I don't really have to worry about it. Since the game is mostly about mowing through enemies, I can deal.
I got as far as the part where the party splits before I called it a night. My brother played Adventure Mode until he couldn't advance any further then forged ahead in the story mode, unlocking the character I really wanted (no points awarded for guessing who). Each stage takes a decent amount of time to complete, much longer than I expected. I consider this a good thing. With four announced DLC packs, I was a bit worried that the game was short on content. Thus far, this does not seem to be the case.
Nintendo/Koei Tecmo are really trying the whole "Who is Sheik?" reveal. Okay. It isn't like Zelda was playing a harp in the middle of Hyrule Field in the opening cinematic (inexplicably) or anything... Or that everyone knows who Sheik is. Unless they go in a completely different direction, this is the weakest plot twist since Sheik's reveal in Ocarina of Time.
The lack of voice acting during gameplay is annoying and baffling. I'm supposed to stop and read in the middle of the game. Get the **** out of here. Link still doesn't even talk since they gave him another fairy. It also doesn't make sense in this game because the whole Link-is-an-avatar-for-the-player thing doesn't apply since there are multiple playable characters. Even more bizarre is the voice narration. While I'd prefer voice acting all around, if given the choice, I'd rather read between stages when I'm not doing anything else than have text block my screen and while trying to glance between gameplay and text. Why is this even a thing? If Nintendo is going to change the series this much, to the point where it's barely a Zelda game anymore, stop holding onto old series tropes.
Ultimately, I'm not disappointed. Hyrule Warriors lacks polish which is strange for a Nintendo game (especially Zelda) but not for a Koei Tecmo game. I'm considering the DLC packs, but I'll see how far I get tonight. I read that you can buy all the packs together at a discount.