I thought it was a bit like DMC, don't those games sell relatively well? If it fails, it will probably be because it's hard to get an idea of direction from what they keep showing. Having flashy bits is great and all, but is there a cohesive style and narrative, or is it just a crazy Best of Wacky Action collage?
The thing about Bayonetta compared to a lot of these other "wacky-Jappy" (™,Prole) games is that Bayonetta doesn't take itself too seriously. It's kind of self-aware that it's being wacky and pokes some fun at itself and at some of the other games. Despite being completely out-there, the story has also been more coherent than the usual fare. The characters are likeable (Bayonetta is kind of a smug bitch, but that seems to be the standard for witches in the game's world) and a lot of the dialogue is amusing (on purpose!). But I agree with Kranz that you will probably find it distinguished mentally-challenged.

It does
not have any teenage, emo, angst-ridden, spiky-haired typical J-RPG cookie-cutter protagonists, however, thankfully. (I guess almost none of the Capcom/Clover/Platinum games do, though)
Without spoiling anything, Bayonetta has a bit of amnesia, so she learns about her past with the player. There's nothing deep here though; the basic plot is that Bayonetta has come back from hell as a kind of bounty hunter, killing angels to avoid torture down below. The game world exists on three planes (human world, heaven, and hell), and there's also purgatory inbetween. I think that's where Bayonetta is, and if you played the demo and were wondering why there's these weird-looking grey/transparent NPCs walking around, it's because they're on the human plane. When Bayonetta talks to humans, BTW, she sounds pretty fucking scary and is like a poltergeist to them.
On the wackyness scale, I'd rate the game a Godhand, but all the enemy types have been more "serious." There's no question that if you're looking for a darker, gorier, moodier, more violent game, that God Of War is going to be your thing. For me, Bayonetta is just more satisfying to play. I would imagine I'll feel the same way about DMC3 and DMC4 (well, DMC4 seems to have emo-Nero) whenever I finally get around to them, too. I can say that on normal difficulty, Bayonetta's been easier to play than the DMC games, but I also hear it ramps up around stage four, which is where I am now...
Also, is it actually playable by people less than great at action games? And I don't mean the win button, but more general approachability. I like God of War for a bunch of reasons, but none of those would matter much if the game wasn't approachable and satisfying even for someone with my weaksauce action game skills.
Absolutely. I don't consider myself to be any kind of master at these 3D action games. You can play this game just doing the same one or two combos (done just like GoW) and nothing else, and still win easily enough. The game ranks your performance and also has online leaderboards, but that's for the hardcore. There's nothing inapproachable or hard to do in this game. My favorite attack so far is the breakdancing gun-play move, and you do that by simply holding down the R-trigger. Tricky!

I've gotten more than one pure platinum award (meaning I killed every enemy with style and without getting hit) using mainly that move. Really, the mechanics at the core are simply attacking and dodging. No blocking or anything; the enemy attacks (and you often get a visible warning of this), you dodge with the R trigger and attack. Timing the dodge right at the last moment will put you into a state where you move normally and everyone else is slow, so you can unleash more attacks. And when you're really kicking ass and have enough magic built up, you can finish off enemies with "torture attacks," which are these wacky cartoon-like violent finishing moves.
Get yourself a J-account and try out the demo...the 360 version, that is. Don't even bother with the PS3 version.