Just how good is Nier: Automata?

Hi guys, I would like to ask you a few things about Nier: Automata for those who play/played it. I recently bought Deus Ex Mankind Divided very cheap but didn't like it very much. I knew this wasn't my type of game but since I could get it for like $10 on PS4 I decided to give it a shot but after spending about 4 hours with it I don't see myself getting through it to the end. It's just too slow, I don't really enjoy stealth games that much and this game promotes stealth over action big time.

I came here because Nier:Automata was on my to-play list for a long time but since I have a ton of real-life expneses and not too much cash on my hands I need to pick my games very carefuly. I'm really fighting with myself here because This game is still very expensive for me, its price hasn't dropped much since release date compared to other PS4 titles. I mean, I could get it but I really need to be 100% sure that this will be IT, so I would like you guys to convince my conscience that I won't regret buying it. Here most important things I would like to know:

1. How good is the combat? I like fast paced sword battles that require skill to master. With good parry and dodge mechanics. I like being able to completely avoid being hit and fast counterattacks. FURI would be the perfect example of a game that is 100% my style when it comes to combat. I also liked Metal Gear Rising, I know NieR is from the same developer, how similar is battle system compared to MGR ?

2. How good is the story? I've heard that the story in this game is super-amazing, is that true? Is it complex and mature? Is it vague like in Souls games that you don't know whats going on? Plz no spoilers.

3. Is it challenging? Let's say I'm good at Action games (I beat all Souls games including Bloodborne and Furi on Furier dif., DMC, Bayonetta, God of War 3 etc. etc.). Just how challenging is the combat in this game? Is it more like Souls-hard or more DMC (not so hard)?

4. How long is it? I'm not going to hunt for trophies, but most likely will do all sidequests (if there are any).

5. Will playing the demo give me glimpse of what this game is and will it spoil me anything? I don't know ANYTHING when it comes to story of this game and I would like to start it blank. Will playing the demo spoil me much?

That would be it, I really want to get this but I'm really short on cash right now and I need to justify myself buying it. Please compare this game to other similar games of that type as this will give me even more insight. thank you for all your replies!