What a snooze fest, this movie has no soul even the voice actors sound bored. The show should've ended with the episode Act Your Age . When they all grew up, this movie is just cashing off nostalgia which explains the positive reviews. I (like many others) grew up with this show it was funny, charming, and had great music this movie seems off like it's missing the Phineas and Ferb spirit. All the character aren't themselves. Vanessa is really off, and the voice actors sound a lot older (which yeah I know people grow up which is why they should've left it like it was 5 years ago) Even the animation is worse, you'd think the animation would improve years later but its stiff and lazy with fancy shading.
I've seen some of Milo Murphy's law which they had a reference to in this movie, I know they had a crossover on the TV show which I didn't like since in an interview the creator said that Milo Murphy's Law would have more continuity than Phineas and Ferb but it quickly went down hill with lame jokes and continuity errors. Even animation mistakes.
The only positive thing I can say about this movie is that I liked some of the songs...If you're a hardcore Phineas and Ferb fan don't watch this movie it will ruin the characters for you.