The people who rail on XY the most are often the JRPG people. It's the people who wanted more compelling character arcs, better difficulty, and perhaps a virtually endless, single-player post-game replay value. Whereas Masuda wanted XY to be a casual, entry level romp for the masses, with outstanding social features for people who play with friends (or competitively). It has great monster variety, many "boutiques" where everyone can make their own avatar, there's some comfy mini-games to play with your bros, better EV systems, faster levelling and such. It's a simple game, but surprisingly replayable on these grounds.
It has technical and performance related issues as a 3DS game (optimization, 3D camera, animations), but these things rarely come up as much as muh difficulty, or muh unfinished plot.
