The classic container
And clay breathes, which means clay containers won't become swamps that drown your prize Mediterranean herbs. They're perfect for plants that require good drainage. However, some clay pots are glazed and these will not breathe quite as well, as the glaze clogs their little pores and there's no such thing as a clay pot exfoliant. On the bright side, glazed clay pots won't need to be watered as often as unglazed clay.
On the downside, porousness can lead to breakage in cold weather areas where the soil contracts and then expands again when things warm up. Check when you buy, because while clay pots made in Mexico and Italy aren't any more cold hardy than a cactus, there are pots made in Germany and colder places that stand up to winter quite well. Of course, if you bring them inside, that's not a problem.
Clay can be heavy - especially the larger pots. Styrofoam packing peanuts used as drainage on the bottom can help lighten the load, or you can keep big pots on wheeled casters. Finally, if you live in a hot, dry climate, the smaller terra cotta pots will dry out too quickly and cook your poor plants.