I saw this at a Watch with Baby screening at 1030 am. I would not recommend the experience. We were a bit late and when the cinema door swung open it revealed a madhouse of babies; screaming, feeding and rolling on the floor. By now it was too late to turn back. Our nine-month old doesn't like busy and loud places, so I spent much of the film holding her at the back and walking up and down the corridor. As a consequence I missed some sections of the film, and might have an unfairly dim view it.
I am confident though in saying that this is a much weaker effort than 2004's Finding Nemo, which I believe has become the biggest selling DVD of all time.
Finding Dory is a further underwater adventure, with some new characters but not a huge amount of charm. The main novelty is that the missing fish this time is ever-forgetful Dory, who tells everyone she has a short-term memory problem. It's a bold decision having a mentally deficient protagonist in an animated film, and is sometimes quite effective, as there is extra pathos when Dory gets lost and feels alienated, but mostly it's a bit annoying with the repetitive gag of her forgetting things and being reminded of them.
There is much madcap chasing, including through a marine centre. The extra scenes on land present a problem for the fish, so various devices are put in place. These include an octopus named Hank, a whale whose echolocation lets him see through walls, and numerous jars and buckets. I'm not a fan of chases in general, and found this a bit tiresome.
The first half of the film is better; the second half gets extremely bogged down with 'tags' and fish being in quarantine and not being in quarantine, and about half of the dialogue is clumsy explanation. The toddler behind me had no clue what was going on, and even her Grandmother's explanations weren't quite right (I read the plot summary on Wikipedia while holding the baby so knew what was going on).
The best thing in it is the grumpy octopus, who piqued my flagging interest. I also enjoyed the Londoner seals, who were voiced by British (but usually American) actors Idris Elba and Dominic West, putting aside their differences from The Wire. Of course the film looked good too, but after the first two minutes you get used to that.
Overall, unlike some other Pixar efforts, this one's just for the kids.