I've never read the manga or watched the movie or anything. What's it about? Clamp is my...uh...it's a vice of mine.
It's about a space-time witch (Yuuko above) of mysterious origin who owns a shop full of magical curios from who-knows-where-or-when and her boy-servant Watanuki. It's fairly episodic, and it usually involves a desperate/flawed customer buying an item from Yuuko to solve some problem in their lives. They use (or misuse) the item despite Yuuko's warnings, and some fate befalls them that serves as allegory for some aspect of human nature. Yuuko obviously knows her stuff and is pretty powerful, but she's also lazy and an alcoholic. Watanuki is kind of the standard loser type, but the comedy around his being pathetic isn't the focus.
It's escapist, but I like the mystical stuff and the Tales from the Crypt-ish themes. The art is gorgeous, too - it's all art nouveau-ish inky blacks and outlines with little shading.