Bayonetta has a lot of things happening at any given time. Guns get shot, monsters get killed, poses get posed, one-liners get tossed around, there's never a moment when things aren't happening. But much like our kawaii Grass-chan, you're never given a reason to care. Why is Bayonetta killing angels? Why are angels killing everyone? Why are some people ghosts sometimes? Why is God evil? What was with that car? Why did Jeanne shoot all those people on that train, and why was Bayonetta there? Where was she going? Where was she ever going? Why did anything happen at all? For an hour and thirty minutes, things are happening, but these questions are never answered. The bad guy is trying to revive the biggest bad guy for... some reason? Is it God? Shouldn't people be stoked to hear that God is coming to Earth? You're never told what the stakes are, so you never care why Bayonetta's fighting. You never see her struggle, so you have no reason to care when she succeeds. You never see her in any danger of losing, so seeing her win becomes meaningless. It just turns into a sequence of events. Bayonetta beats this bad guy, so now she's going to fight this other bad guy, and she's going to win but we're not quite there yet. There's nothing to think about, no surprises, no doubt, no reason to keep watching these things happening. It's just grass growing.
I haven't played the game that Bayonetta is based on, so I don't know how this adaption compares to the original. But I know immediately where all the emotional investment went. When you play a game, you supply the emotion. Just making progress gives you a reason to care, since you've now invested your time towards beating the game. You learn the price of failure if you die, which adds excitement to the fights as you try to avoid that same failure. You learn the capabilities of your character, what she can and can't do, and you add your own skill in order to overcome the obstacles presented to you. Just playing the game is enough to make you care. The story and cutscenes are nice rewards for your progress, but the goal is progress itself. This is why a straight adaption just doesn't work. There's no inherent difficulty in watching anime (except for downloading codecs and stuff, but you get the point). Once you start watching, you won't fail and have to start over if you don't beat the boss. Your skill has no bearing on whether or not the protagonist succeeds. You have no control over how or why things happen, so you need another reason to invest your time. You can't help the main character fight, but you can still care if they win or lose if you're given a good enough reason. Bayonetta just doesn't give you a reason.
Bayonetta isn't ALL bad. Norio Goddamn Wakamoto voices one of the leads, which makes absolutely any show better (see Wizard Barristers for an example). The art is good, if you've ever seen a Madhouse production it looks exactly like that style. Bayonetta has some killer tits. Beyond that, it's hard to think of any other positive points.
Should you watch Grass-chan Adventures? Maybe, if it ever comes out. You'd probably feel the same way watching Bayonetta. Should you watch Bayonetta? Not really. The only thing this movie really has going for it is the action, which is just bland and predictable. The story is a jumbled mess, the characters are boring, and the things that happen just aren't interesting. Your time would be better spent watching something else.
