I was disappointed with the rivals. I never got to face Serena early enough to see her unevolved starter form. I wished Trevor and Tierno didn't have the other 2 Kanto starters that I didn't pick.
I didn't like how Tierno's progress was never gauged against you. I think if there was a new Contest feature involving dancing, it would have been fun to compete with him. From battling against Serena, completing the Pokedex against Trevor, and experiencing a lot of storymode alongside Shauna, Tierno didn't offer much.
I don't like how Ditto is such an exclusive Friend Safari pokemon. I think it should have been the "free" bingo spot, where when you first walk into the Friend Safari, you just start off with one even if you've never met any friends.
The payouts of Battle Chateau Writs and Sushi High Roller are disappoint.
There are many interfaces which can be organized, such as your Bag pockets or even the pause menu buttons. Yet you can't organize things like the "Organize Pokemon" in your PC to be the default instead of Deposit/Withdraw. Can't organize your favorite clothes to be on top of the junk you bought for cloth completion. Can't organize your favorite Friend Safaris on top. I seriously don't get why out of everything, the pause menu was given that option.