I love it. But I have a sense of humor, I don't take games too seriously, and I'm able to enjoy games that aren't "AAA" titles. I'm also old enough to have been around when there wasn't a video game industry as it exists today. Games were a diversion, and there weren't websites, magazines, and tv shows telling consumers what they were allowed to like if they really were a "gamer."
Is it repetitive? Yeah, of course. But so are Halo and Call of Duty, and you don't see that stopping people from playing that hours on end, do you?
It's pretty fast paced and fluid, which is exactly what you want in a hack & slash game. I played Samurai Warriors 2 a bit last week after playing Onechanbara, and it felt really slow.
Many of the achievement seeking crowd gripe because the achievements aren't story based, and so they just give up on it. Truth be told, other than two or three of the more difficult ones, most of the achievements are easily farmed once you know what they are and how to get them.
There's also a free illustrated PDF guide with full walkthrough, tips & tricks, and achievement guide available on the publisher's website (D3 publisher).