Went and saw this last weekend. Definitely highly recommended, with a great story and excellent characters. Florence Pugh is worth the price of admission on her own and definitely deserves a long stay in the Marvel Cinematic Universe.
As always with Marvel movies, you should stay right to the end of the credits; there's a scene that is well worth seeing.
Also, Loki is well worth watching on Disney+; it very much fulfils its glorious purpose and while Tom Hiddleston is brilliant, Sophia Di Martino is the icing on the cake.
All in all, Marvel is doing very well at the moment and What If? in particular looks very interesting.