I wouldn't say that the rockwork is poor, in fact, I would say it is quite attractive, but you asked for a comparison between Potter and FLE. Well, first of all, I don't remember all that much rockwork at Potter, so I can't really compare it. However, it would be difficult anyway because Potter is a land in and of itself with theme's that are directly associated with Potter. FLE rockwork is more of a faux land decoration in that there is no real consistency of theme there. There is Mermaid and Belle and soon the 7 DMT. All they can do with the rockwork there is create the necessary scene for each attraction. It's not Little Mermaid land. Once the Mine train is done then it becomes even more diluted because then FLE becomes just a part of the entire Fantasyland picture. Still the overall appearance should be improved with the removal of the construction wall.
Don't quote me on this, I tried to find the reference but was unable, but I think that it was just a little over 3 years to completely build EPCOT. Disneyland was completed in 1 year. Is 4 years a bit much for FLE? I think and argument can be made that it was way too much!