We bought one in Morocco, but it already cracked on the hob. It was cheap in Morocco (like equivalent of £5) & DH thought it was okay to use on the ceramic hob. We bought one like what the locals suggested - it's plainy plain. They said the decorative ones are meant to be just that - decorative, whereas the plainer ones are for cooking - from among those produced & sold in Morocco.
It's not broken through so DH just warms it & uses it to serve tagines now.
You don't need a tagine to make tagine though.

In Morocco, they tend to cook with them over charcoal fires.
Tips the Moroccans gave us - brown the onions & garlic on a med-high heat, then brown your meat. That's the heart (I mean the centre) of the tagine (if you're doing a meat one anyway), then turn the heat way down low & pile the veggies around. Cook long & low & slow. Oh yeah - the dried fruits are nice in there too - prunes, apricots, preserved lemon for chicken, etc.