I have a small Le Creuset and two bigger Chasseur cast-iron casseroles with lids, and I don't notice any difference between the two brands (except that the latter were cheaper!). The medium to large size ones are extremely useful/versatile.
I've also got a Le Creuset griddle pan, which I like but don't use that often, although I've noticed that the bottom of this seems to have burnt quicker than the casserole ones.
I wouldn't bother with their earthenware stuff - I think you can get cheaper, just as good quality earthenware in Sainsburys and JL, but I do find the cast iron casseroles very useful.
That said, the plastic handle/top on the lid of one of them did explode once, after a while in the Rayburn, but I don't know if that's a reflection on the stupid Rayburn rather than the dish itself...
Limitedperiodonly and Ponders - I was cooking at a friend's house with her oval one this weekend, and really liked the shape - it was easier to fit other stuff on the hob around it.