I bought this game the day it dropped and initially liked it mostly due to the changed combat system. That did not last.
There are many issues I have with this game but I will go over the big ones.
1. The map is far too small. Squeezing in wild zones into an already tiny map just made it feel much smaller and overall the "parkour" content did not improve this, in fact it felt half baked. I can't climb up something shin high but I can jump off of a building?
2. The alpha pokemon just feel like a poorly planned gimmick. They are just larger, often worse looking pokemon. Originally I thought it would be neat if they were more powerful versions of the species, they weren't. They were just larger, and had an off class move. They did not improve the game and they were far too easy to find.
3. The mega-evolution felt constricting. By introducing this element it made it feel like I had to use pokemon that could ALSO mega-evolve, making some of my favorite pokemon in my team less useful for no real reason.
4. The graphics are terrible. Enough said. They are not good.
5. The game was far too easy. At no point did I feel challenged, in fact I was always 15-20 levels ahead of every opponent. In every single battle I could simply use one skill and one shot almost anything.
6. It felt targeted towards e-girls. I get that this is a kids game but this game 100% felt like it was targeted specifically towards e girls. There was nothing "cool" about it, it didn't feel like anything I did had any real value in the world of Lumiose, in fact most of the battles would be hap hazard and revolved around the streamer (spoiler) or the tournament. And the verbiage was awful. I can't believe that we haven't also figured out how to add voice acting to these games.
Overall, I originally enjoyed the nostalgia but this was strongly overshadowed. All of the attacks felt the same, the pokemon looked cool and the new combat system was interesting but this just felt like a shell of a game or like an expansion of a better one.