It's exactly what you'd imagine, in a good way. "Seiyuu" means "voice actress". It's about the lives of three seiyuu, struggling to get by in a mercilessly tough industry. It's likeable, funny and occasionally a bit scary. (Our heroines aren't exactly failure-proof and it can be mildly terrifying watching them try to do something for the first time.)
What makes this show worth watching, over and above its charm and humour, is the fact that it's written by a seiyuu. It knows what it's talking about. It's full of weird details and insights that you wouldn't have expected, some of which seem to contradict each other because not all agencies, studios and production companies work the same way. Some have internal evaluations. Some expect their newbies to come into the office and stand there in a line when they've got no work. Some cut their failures loose and others will happily leave you on their books for ever.
That author is Masumi Asano. She's a seiyuu and works in this world, but she also writes about it through a self-published comic series (doujinshi). (Her artist is Kenjiro Hata, the creator of Hayate the Combat Butler. I've seen it said that this show is set in the Hayate the Combat Butler universe, which seems a bit weird but I can't comment on since I've never seen that show.) Anyway, this doujinshi drew enough attention to get this anime adaptation, which I think is cool. Asano can also be heard in all of its episodes (as is right and proper), but only in supporting or cameo roles rather than as one of the leads. Those characters are:
FUTABA ICHINOSE - nervous, bad at dancing and liable to turn into a brain-frazzled wreck if confronted with anything she hadn't anticipated. She has the least experience and confidence of the three main characters. She's a lovely girl and you want her to succeed, but she can be a bit nerve-wracking.
ICHIGO MOESAKI - can be kind of painful. She's given herself the sickeningly cute public personality of Princess Strawberry from the Planet Strawberry. She thinks this makes her adorable. (We'll also discover that she's a pretty serious otaku, which on reflection pretty much had to be the case.) However she's also serious about what she does, works fantastically hard and is a kind, supportive friend and colleague. She could give confidence lessons to Futaba. It's just that she's a bit of a loon.
RIN KOHANA - a veteran who's been in the business for ten years, despite being only fifteen. She hasn't even started high school yet. She teams up with Futaba and Ichigo, being a shy, demure girl who's struggling to juggle schoolwork and a career.
The show even has famous names, playing themselves. I think there's about one real seiyuu an episode.
The show's simply these girls' professional lives. They keep doing things they've never done before. We see the differences between doing, say, a voice for an anime, an audiobook, a computer game or a dubbed foreign film. They get recruited into a three-girl seiyuu unit called Earphones (which the show's three voice actresses turned into a real unit and they're still performing together under that name). They do live radio shows (which nearly kills Futaba) and stage shows. It's all cool and interesting. A seiyuu's life will contain a greater variety of jobs than you'll have considered and is liable to contain much, much less glamour than a starry-eyed newbie might hope. Sometimes it's silly, but in a realistic way. Japan can be strange. That's here too, portrayed in clear-eyed fashion by Asano.
Oh, and don't expect to be able to live on your seiyuu income. You'll need a day job, perhaps in a factory or a convenience store. Try not to get fired from it.
Don't be put off by the fact that it's by Studio Gonzo, by the way. It's a slice-of-life show, so Gonzo storytelling isn't a factor.
It's a gentle, enjoyable show. The girls are nice and can be downright adorable in their ability to get absorbed in their work. It's funny watching themselves in some silly anime or other, for instance. ("Do you think that's the voice of a woman with big boobs?") There are times when I just about died laughing. Mind you, they're also liable to petrify into a solid crystalline cringe of terror. Their first attempt at anything new is likely to be a disaster... but one of the show's messages is that stars are no different from the rest of us. While our heroines are squealing in the presence of their childhood idols, those megastars are likely to be reassuring them with stories of their own insecurities and depressions. It's a brutal industry, but it's also full of lovely people who are always willing to offer advice or guidance. Our heroines learn and grow. I liked it a lot.