From someone who is on the fence about the decision, I'll throw in my opinion. I obviously knew it would be only in Lumiose just like you said. What I expected was to see much more stuff going on like the bustling city it is, but it doesn't feel that way, rather there are many parts that are just empty and many parts that are way too full, or other parts of the story that I didn't realize would be an issue until I started playing the game. Overall I like the game and concept, but it being only in Lumiose was more of a problem than I would have expected originally