It's based on a novel. Not a light novel series. A novel, written by Megumi Hatakenaka and published in 2007.
That said, I'd probably give it a seven out of ten. It's civilised and nice, but not particularly urgent. I enjoyed it, but I never felt compelled to marathon it.
It's set in Edo's Fukugawa district in... oh, gosh, I'm not sure of the year. There are samurai, but everything seems peaceful and there are no swordfights. Let's say the 17th century. Two not-siblings (Okou and Seiji) run a rental shop where the stock includes tsukumogami. That's just one of many, many cultural references that had even me looking stuff up all the time. History, netsuke, okappiki, literature, mythology, hanging scrolls, kiseru, Edo-era fires and migration causing people not to keep many possessions... wow. It's educational. If you're not Japanese and you're planning on watching this anime, then you'd better be interested in Edo-era culture because you're going to be learning a lot about it.
I'd better explain tsukumogami, although the term's been used for various different concepts in Japanese mythology. This show uses the best-known one, i.e. tools or things so old that they've acquired spirits. Imagine a Disney talking teapot or something. It's like that. They come alive and talk when no one's looking, although our heroes' ones get a bit sloppy around them. The Iida-ya shop's tsukumogami include a kiseru (pipe), a hanging scroll of the moon, a comb with a rabbit pattern, a doll of a beautiful woman and a bat netsuke (a little carved fastener).
Okou (f) and Seiji (m) are adopted siblings. There may or may not be romantic feelings between them, but the path of love is complicated in this show. (Okou has a pretty serious admirer, although it'll take a while for us to get at the backstory behind that.) Seiji's a bit of a detective on the side, especially with tsukumogami to hunt for clues if you can talk them into it. He's a nice guy, if a bit prim and over-protective on occasion. I wanted him to piss off in ep.4. Anyway, people quite often ask for help and their problems generally end up being love-related. (Good grief, some of these men are pathetic.)
Most of the couples and potential couples get sorted out by the end of ep.12, but some are beyond help in a tragic way and others are only one-sided and/or have some probably unforgivable obstacles in their way. Ep.8 made me sit up. Ouch.
I also liked the theme song.
It's a civilised, sometimes amusing show. The tsukumogami can be childish and, uh, of variable intelligence. (Their reaction shots also made me laugh in ep.11.) It's pleasant to see such a civilised portrayal of the samurai era, with people peacefully buying, renting and worrying about how to talk to a waitress they're in love with. The show can sometimes feel like an episodic mystery-of-the-week (although those mysteries can be interesting), but characters we've met once are liable to return as they'll have failed to sort out their romantic lives. Okou and Seiji aren't the show's most gripping characters, to be honest, but they're likeable and I wanted them to be happy.
The last episode ties things up pleasingly. I don't know if you'd ever feel the need to watch this twice, but it definitely has charm.