This is absolutely one of the most emotionally engaging shows in any medium I've encountered in years. It frequently accomplishes this in a most unusual way (by grabbing ones emotions by the throat, beating them upside the head with some rebar and then staking those concussed and bleeding emotions to a fire ant hill). Yes, this show is quite hard to watch at times, but is extraordinarily well paced and well thought out. Its tone and themes remind me of Ellison's Delusion for a Dragon Slayer, in that the protagonist start's out a person of, at best, mediocre character and quite unfit for what he must face. Unlike that tale however, this is a story about redemption and the fact that we can change. Subaru, the hero, is a really interesting character who learns from his numerous and painful mistakes. He comes to confront his myriad failings and change what he can, and work around those failings he cannot.
Strong women are not a novelty in this day and age, but the heroines (and villainesses) in this show are some of the best, most realistically portrayed in any fantasy series. They are written and talk like actual. umm, women, Emillia, for instance, is quite the awesome and noble character.
And it was nice to be reminded that she can righteously kick ass.
She also comes off as a real woman despite a remarkably limited time onscreen. At one point she saves Subaru's butt for approximately the umpteenth time and he apologizes for thus imposing on her. She replies that an apology is unnecessary...but a "Thank you." would be appreciated. Exchanges like that, actual things that actual humans might actually say, really make this show.
Re: Zero is heartbreaking and terrifying at times, far more so than one would expect given the show's central conceit, but the fact that they can pull that off is a remarkable achievement. Any show can be grim and gritty, but this show uses the horror as a way to move the characters forward and contrast to the show's highs. The writers here do so masterfully.
The show has a bit to say about the nature of love and its complexity including its selfish component, and how pride can toxify anything. The show also deals with the more painful sides of love such as loss.
...and the heartbreak of the friendzone.
Oh...my GOD what an awesome character Rem is. Although she is also very well realized and exquisitely written, her adoration and servant outlook comes off as perhaps too möe for comfort.
However, her character is really, really well written and she is a truly admirable and courageous character and cute as a button and just all kinds of awesome.
But this is not a harem show, and the one thing that kept Subaru going was his love for Emillia, so this.....OH DAMNIT!!
Re:ZERO Starting Life in Another World is a superbly engineered emotional rollercoaster that may cause nausea and night-sweats, but unlike most rollercoasters, which take you back to where you started, this is a terrifyingly thrilling journey to a much better place
While there are some unresolved plot threads, the ending is perfectly satisfying as is. If they decide to do more I'll definitely be watching it.