I grew up watching Pokemon during it's 2nd gen. and even this movie hurts to watch sometimes. This movie is much like other pokemon movies. The storyline is simple enough to for anyone to follow, has decent morals for younger audiences, and the art style is a noticeably better than how it would usually look in the it's TV counterpart. Anyone who's watched both the TV show and the movies would know that there is little to no continuity between them, other than the TV show with Mewtwo (in the 1st gen.) and the 1st 3 movies within the 3rd gen. (Diamond and Pearl). However, thisis where I find fault with this movie in particular.
Mewtwo is one of the few characters in the pokemon movies that always seemed to carry continuity with him, by having him and Ash always remembering each other. For whatever reason this is thrown out the window as Mewtwo practically ignores Ash. And as much of a nitpick this is, its a major distraction for fans that have watched and enjoyed Pokemon for years.