I'm surprised by how many people played my demo with kb&m rather than controller and I'm glad to see that you all found the controls pretty agreeable overall.
holding down the block button changes nothing, it only cares about your initial button press. and the timing is not too far from what it is in dark souls 1 and demon's souls, which is that you have to press more or less when the enemy's weapon is about to collide with you, otherwise you get a regular block.
Doing both things with the same button but timing based is pretty common in action games, idk. Even sekiro works like that