Just finished this whole series. It definitely had some redeeming qualities. I'm sure it'd hit a lot of people's checkboxes with its aliens, alien politics, androids, battle scenes, fanservice, romance, slice-of-life, and the near end of the Earth itself. It had a little bit of everything. It's also only 8 volumes long: A reasonable length for a manga series.
If you're interested in watching a battle android that looks like a cute girl wearing a maid uniform go back and forth between the slice-of-life moments of taking care of a teenage boy and battling other androids and aliens, this might be for you. Interspaced between all of that is the tension of knowing throughout the whole series that she has only a limited amount of time left before she no longer functions. And the books constantly remind you by telling you exactly how much of that time she has left at regular intervals.
Personally, the one part of the manga I hated (beyond the fanservice— which I never like but am capable of ignoring as long as it comes in reasonable doses) was the ending. I can't get into it without spoiling the whole thing, but I thought it was a disservice to the main character.
Battle android Mahoro was created by the government to fight aliens and she's done an excellent job. However if she continues the way she is she'll die in 37 days. If she stops fighting she could live 398 days. The government giver her the choice of how she wishes to end her days. She decides to retire and become a domestic servant to orphan teen Sugaru.
Sexy rom-com ensues as Mahoro falls for her master and has to prevent his cougar school teacher from having her wicked way with him. By the end we begin to realise that perhaps her choice in Master wasn't quite so random after all.
Normally I'm not so keen on this type of sexy rom com manga such as Love Hina, Tenchi etc. However I found Mahoromatic surprisingly enjoyable. The story is fun and the characters have some depth. It does have a fair bit of nudity and suggestion to merit is 16+ rating.