It's okay. Maybe a little tamer than I'd expected, but okay. I quite enjoyed it.
It stars angels and demons who don't act as you'd expect, like a cross between Panty & Stocking with Garterbelt and Himouto! Umaru-chan. It's all mild and family-friendly, though. The joke is that the angels are terrible people, while the demons are too nice and/or stupid to be evil. Their idea of wickedness is not buttoning up your cardigan, or putting a bottle in the recycling bin with its cap still on. Our heroines are:
GABRIEL (angel) - the title character, obviously. When she arrived on Earth, she was noble, selfless and ever-smiling. Unfortunately she then discovered internet gaming and turned into a grouchy, lazy slob who mooches off her friends, keeps her room like a rubbish tip and cares only about computer games. When particularly grumpy, she'll be tempted to destroy the world by blowing the last trumpet for the Day of Judgement.
VIGNETTE (demon) - she's lovely. She's the one and only kind, responsible and intelligent cast member, looking after Gabriel and occasionally worrying about the fact that she's not demonic enough.
RAPHIEL (angel) - sadist and stalker.
SATANIA (demon) - gloating, over-the-top ham who believes herself to be the Arch-Demon and Almighty Destroyer of Mankind. She'll brag about how evil she is because she didn't her homework. She's also very, very, very stupid and is continually having her bread stolen by a small dog.
This is quite funny. There are some good jokes in here, but the show's also not pushing its premise very far. It's just a slice-of-life schoolgirl comedy with a supernatural angle. The demons never do anything genuinely bad, while the angels' bad behaviour is restricted. Gabriel is lazy and irresponsible, not evil. She's capable of doing nice things for others, although you'll have to wait a long time to see it. Raphiel might arguably be evil, perhaps, but only when it comes to teasing her immortal, supernatural friends. (Her favourite victim is Satania, who's so dense that she hardly ever even realises.)
The show's quite good. It's also harmless, being a reasonable choice to watch if you're looking for some anime to watch in public and you think your housemates and/or children might object to much of what gets released by the industry. I didn't think it was as good as Himouto! Umaru-chan from the same staff and studio, but I watched it. I might even go looking for the OVAs, although I wouldn't really be bothered if I couldn't find them. A lot might depend on your personal reaction to our dodgy heroines, perhaps, since they're almost all self-centred idiots who do nothing but make trouble for their friends. It might also be a simpler show to watch if people were outright evil, but personally I think it's eventually obvious that they're good people underneath, really. (Except Raphiel, perhaps.) Ep.11 (the dog episode) makes that clear.
It's fine. Seeing the girls go home to heaven and hell for the holidays in ep.10 was quite funny, as were Gabriel's fitness tests in ep.8 and Tapris's visit to Earth in ep.5. (She's come straight from heaven as a fangirl of the saintly Gabriel we saw at the start of ep.1.) It's not a brilliant show, but you could do worse. Try an episode and see what you think. Ep.1's pretty representative of the show as a whole.