How exploration heavy is Nier?
There's some exploration, but it's not really the focus of the game. The cities and fields are pretty open, but the world isn't particularly large or anything.
Lots of quests?
There are a lot of sidquests, but most of them are terrible fetch quests that send you into a dungeon to farm 10 rare items that have a 2% drop rate. There are several good quests, but most of them suck.
How deep is the combat?
Not deep at all. There's like five or six weapons styles (spears, swords, axes, etc), they all have one combo, one special attack, and one jump attack. There's also some magic spells you can mix into your attacks. Enemies have pattern-based attacks that you can avoid by rolling, like most action games. As a whole, it's pretty shallow, but still fun.
How good is the story?
Great. Best story in a game in at least five or six years. Make sure you play it at least twice though.
Both Bayonetta and Vanquish are amazing games, but Bayonetta has more content by far. Bayonetta is like DMC, with a deep combo system, lots of enemy variety, and a pretty good (but easily exploitable) scoring system. Vanquish is like an arcade game. It doesn't have a ton of content, but it has high replayability and high difficulty (it's much harder than Bayonetta). The scoring system in it is pretty simple, but it works well with the game. It's based entirely on how fast you can complete a stage while killing as many enemies as possible.
To summarize, Bayonetta and Vanquish are what single player gaming is all about.
