Jeremy Crabb’s review published on Letterboxd:
As a lifelong (or at least life from the age of 5 onward) Phineas and Ferb fan, I'm happy to report that this is everything I could ask for in a Phineas and Ferb movie. This film invites you back into the world you love with the characters you love in such a way that it feels like they never left, even if the show wrapped years ago. The plot is pretty cliche and predictable, but it's the addition of that classic Phineas and Ferb humor and heart that make it really work. This film is actually pretty hilarious. I found myself laughing quite often, which is something I realized about the show too. The humor of the show actually ages beautifully, where I think it's actually funnier now than it was when I was younger, and this film gave me a lot to chew on in terms of clever jokes, and really clever writing in general. This was honestly a blast. If you are or were ever a fan of the show, definitely give this a watch. I hope this isn't the last we see from these characters and this universe because this film proves that they've still got it.