While I definitely think this game is hard, I don't think it is anywhere near as hard as Ninja Gaiden. I beat all of the story mode in about 4 and a half hours the first night I had the game, alpha is hard, but once you learn how she fights she can be managable for 1 win. I am not that good at DOA either. Never have been real competative online. Now time attack on the other hand is a pain. Beating Alpha-152 twice is hard. Especially with the slower characters. The difficulty is actually nice, not so easy to just burn through single player and prepares you a little better for online.
Oh, and am I the only one who actually finds counters easier to pull off in this game than in the previous titles? I know the window is supposed to be smaller, but it sure doesn't seem like it. I use the D-pad, much more precise control, really makes it easier to reverse.
On a side note, one of my biggest complaints about video games these days is how short and easy so many games are. I am sorry 10 hours on the first play through, or 6.5 hours in some cases (I'm looking at you ultimate spider man) is not acceptable. The main story and missions should be at least 15 hours. Then your side quests and some replayability extend it to at least 20 hours. If you can't get 20 hours of play in 3 years of development you shouldn't be making games. Plus you make games so easy that any decent player can just blaze through them with ease on the first play. Not acceptable. Difficulty and smart AI is what makes games like Ninja Gaiden or Halo on legendary fun.