Kalos is a really good region to explore, especially in it's first half. It does seem the region was rushed, though. The time it takes for you to get the first four badges is almost twice the time to get the last four. The regional dex division is an indication of that: the first dex is comprised of Pokémon you get from the start of the game till halfway on your journey to the second gym, the second dex from this point to the fourth badge and the third dex for the rest of the game. I think the original plan was for the game to have four dexes (600 Pokémon), considering the Pokémon distribution in the first half of the game. I believe some part of Eastern Kalos was cut from the games, probably between the sixth and the eight gyms (or maybe it was a post-game area). I think Pokémon Z really had the potential to fix this region, especially with the addition of this cut content.
To be fair, these games had the best online of any Pokémon game and a lot of cool aditions. At this time, the Exp. Share could be kept off at all times. The only things these games needed to be great were a lot more challenge and a much better post-game. I think if Pokémon Z was a thing, generation 6 would be much more well regarded.