Everybody seems to call it Chaouen ("peaks"), which was its old name before the Spanish changed it to Xaouen, and then in 1975 it became Chefchaouen (شفشاون in Arabic; ⴰⵛⵛⴰⵡⵏ in Tamaziɣt - let's see who's got all the fonts installed!) Anyway, now it means "look at the peaks" - was that some early tourist marketing?
It's ridiculously beautiful, sitting at about 1500-2000 feet above sea level on the edge of a mountain, with a blue-painted medina that dates back to 1471. It's also full of cats, and so is probably one of the most Instagrammable places on earth. The people who live on the street with the flower pots have presumably decided that they want everybody to take pictures of their street (and there are a lot of postcards and crappy tourist art available in case you can't get through the throng to take your own), although I think I prefer the ultramarine street we found towards the top of the medina,. Not sure about their decision to use Comic Sans on the street signs, however...
A few quick words of advice for travellers: we took the regular bus there for 20 dirhams each and then were persuaded that a 30-dirham taxi ride to our hotel was sensible - see pictures below. Not walking uphill from the bus station was very sensible (Google says it's a half-hour walk, but that doesn't count the 500 feet or so you have to climb), although the actual fare is more like half that. We took the CTM bus back to Tetouan which was much cleaner and more spacious, for a mere 25 dirhams a head.
The Bar Oum-Rabiá appears to be the only place in town that you can get a beer. The Lonely Planet just says it's "a very masculine option" - that's the entire entry - but we had a pretty good meal there, as long as we could time our bites between the clouds of smoke from the table next to us. There seems to be a protocol demanding that they serve food with drinks, so every time I ordered another (tiny) beer another plate of food arrived. They started by bringing rice and salad, but after a few beers we got to the sardine tagine, which was surprisingly good. Oh, and don't believe the extensive drinks list: we had the choice of Flag Especial or Johnny Walker.