I've been dealing with Worldworks for a couple of years now. In general, their products are excellent, although I admit my building output is very low. (Lots printed but little built). They are quite detailed models, running to a couple of dozen pages in some instances, so they are not 'print, cut, fold, glue' designs. They take some thought and a bit of work to assemble but the end results can be stunning. The stained glass windows in some sets are gorgeous. Be warned, though. Some of the buildings, like the Cathedrals and the Manor, are huge!
Any one in particular you're looking at? I have most of them so can give you an idea what's involved before purchase.