The event was ok.
Personally still being only Kanto champion and starting this year, i didnt have access to mega Pokemon etc.
I 'll compare it to halloween though since i completed that too and i can have an opinion there probably.
As part of enjoyment it was fine and new place hype etc. The trainers scaled right away a lot while in halloween it was a slow start up to 120 lvl boss fights.
The low level trainer battles were good to have and nice to replay. I tried to use the extra ammount of exp i could get from them after every week reset.
If the event is recommended for everyone, i feel that at least the battles could be a bit easier, with some key battles to take some time.
The story was fine didnt pay too much attention though to judge.
I wanna say though that the forest maze part that you had to find your 3 randomly generated buttons wasnt fun personally. I get the idea why it was done, but still it was a pain to find them for people trying to complete the event. Personally, it took me around an hour to find the last after i heard what are the possible ones. I had found everything but the one i needed. If they aint randomly generated, at least people can look up to find the one they are missing.
The zones personally are very nice to be large wide areas without too much grass. But next time it would need some more pokemon centers or teleport options like halloween had. In the start it was nice, but after starting grinding it becomes just a problem that shouldnt exist.
Some nice options would be for guards like the ones in matsuki, to disappear after you complete the event, there was no reason to have to avoid them, just to get to the grass later to farm. This was done in halloween event, i dont know why you didnt continue this way.
Last ideas i would like to recommend :
1) dont ask for that much money to re-enter event area. Like as a kinda new player i cannot afford that, so i can only go back to Vermillion only if will farm dig spots or i really must to.
2) even if you didnt do pikachu as January's world quest, it would be nice if it still was a pokemon found in the event. A lot of people probably wanna participate in the world quest.