It's one of the best anime of the year. That's not hyperbole, by the way. Look at reviewers' "Best of 2018" lists and you'll find this. It's about schoolgirls going to Antarctica.
It's good because it's at once charming and unexpectedly dark about how people are. The girls are adorable. You'll love them all. It's always fun spending time with them. However all those warm fuzzies are backed up by sharp, strong writing that avoids safe options. The girls can be petty, rude, tactless and/or jerks. Shirase's seduction plan in ep.2 is appalling, although of course it immediately fails because they're all hilariously bad at it.
Among other things, it's a show about friendship. That might be anime's favourite theme, but this show is for once exploring it instead of just waving it like a magic wand. There's an interesting discussion in ep.10 of what a friend is and how such relationships differ from more clearly defined ones, like a parent or a spouse. The girls all have different definitions of it. Yuzuki's a celebrity with hang-ups so weird that she tries to hand out contracts. Kimari and Hinata have friends back home... sort of. Ish. The show has things to say about what a "friend" can really be. Sometimes there's forgiveness that isn't wanted and sometimes there's, uh, the opposite. Bloody hell. "Unlike Hinata, I'm a real jerk, so I'll say this to you straight."
As for the girls themselves, they never stop taking the piss out of each other. They mock each other, say incredibly rude things and draw on each other's faces. Apparently the director based them on her own best friends in high school. It feels real. We're not watching generic blobs of niceness, but instead utterly believable people who know each others' bizarre, unfriendly qualities and are friends anyway.
KIMARI is theoretically the main character, but she's also the only one who's not screwed up in some way and to be honest you'll probably end up remembering the other girls better. (She does have focus episodes in the season's first half, though, and they're very good.) Kimari can make you wonder if the show might be more about group interactions, rather than the girls individually. That said, though, she's also the kindest, most forgiving and loopiest of the girls. She's got no particular reason to go to Antarctica. She just decided one day that she wanted to do something exciting, whereupon she met...
SHIRASE, the anti-social girl with a bad personality. She's the one who's determined to go to Antarctica. (Her mother went on an expedition there three years ago and never came back.) Shirase's been doing part-time jobs, saving all the money and ignoring everyone at school who laughed at her. She wants to know what happened to her mother, but she also wants to gloat at everyone who told her she'd never make it. (She's also rubbish at social situations, so of course her friends keep pushing her into them. I see no reason beyond sadism for making her do live internet broadcasts.)
HINATA is a high school dropout. However it's easy to forget about this because she's short, cheeky and super-energetic. Surface-Hinata and real-Hinata are very different. Close attention will reveal that she's the cleverest and most mature of the group, for instance, although admittedly that's not saying much.
YUZUKI the child actress. She looks like the sensible one, but she's got some weird stuff in her head.
It's not just the writing that's impressive, though. The show's also beautifully made. The animation's as expressive as the script, with the opening titles being endlessly watchable for how much fun and characterisation the show can find in four girls being goofy. Look out for the running sequence in ep.2.
It's a very simple story, albeit richly told and full of humour. Schoolgirls go to Antarctica. (This is realistic, by the way, and there's a lot of work to be done just to get on that icebreaker ship.) That's it, really. They don't save the world from aliens or anything. However I'm pretty sure that if you went to Antarctica, you'd find your life being turned upside-down and you'd have some stories to tell afterwards. That's the case here too.
It's got emotional depth, but also lots of laughs. It's got self-loathing, pent-up bitterness, grief and inappropriate interviews. It's exploring unusual kinds of Not Nice, while also always being happy and lovely to watch. It's great.