Nier isn't the greatest game in the world, thats for sure. The game mostly suffers negative reviews due to it's repetitive and dull combat, it's pretty much a water-downed hack'n'slash where you fight countless of unimaginative enemies that all look the same. I've also heard countless bashing against it's simplistic linear side-quests and that they really have no thought behind them, which is also true (They where very tedious). But when you play a game you should always try to look behind the bad stuff and try to see the good points about it.
Long story short, you play Nier for it's story, it's world, setting and context. It truly is one amazing tale, packed with one of the best OSTs of all time (IT even has its own Wikipedia page :3)
The game isn't for everyone. It's okay to hate it, a lot of people do. I'm glad that you gave it a try though.
Go back to Chrono Cross, I recently finished it again - awesome stuff.
Or go play Enchanted Arms made by the "ever-so-brilliant" From Software :3