Mark Harrison’s review published on Letterboxd :
[IMAX 3D] A character driven sequel that takes extra care to give every one of its major players a distinctive arc, sometimes at the expense of both momentum and suspense. Neither the script nor the soundtrack are as good as the first time around, but it's testament to how good it is anyway that I was openly weeping from the moment that final Cat Stevens song started playing, up to the brilliant final shot before the credits.
It has a little of Marvel's second movie syndrome (on which basis I'm expecting that Vol.3 will be absolutely blinding) but it's comfortably better than either Iron Man 2 or Thor- The Dark World. I hope the Avengers team-up won't wear out their welcome, but there's an emotional connection to these characters that goes deeper than the continuing novelty of its blockbusting weirdness.
We are Baby Groot.