The people rating this series one star are some of the dumbest people alive. If you actually read through the arguments of lowstar reviews, you can tell that these people either didn't watch the series or they're parroting nonsense from someone else that didn't watch the series.
-----No, Rezero is NOT a harem. Never was and never will be.
-----No, Subaru is NOT a dumb character. He makes rash decisions over the course of 4 or 5 episodes under extreme stress while mentally broken; Anyone under the same conditions would be doing the same.
-----No, no actual person can stop where they are, "train" a little, and get stronger. The Re:Zero world is meant to be relatively grounded in realism, and the nonsense anime training arc is not realistic. To the people who say Subaru should "train": Put your Cheetos down, wipe the gravy off your lips, get off the couch, and pick up a sword. Train your swordplay for a week or month ((without the internet, Subaru doesn't have internet)) and then challenge an actual expert to see how it goes.
-----Yes, Subaru NOT choosing Rem happened and was GOOD. Rem was never on the table as a character Subaru had feelings for. Just because someone is obsessively in love with you, that does not obligate them to having their feelings returned. Imagine irl some 300 pound 50 year old man is obsessively in love with you and watches you sleep through the window. Is it still cute? Is grandpa still best waifu? No? But he's SO loyal and he loves you no matter what, even if you don't love him. Grandpa is always going to be there with you, watching you. Loving you.
Phenomenal series.