With so much talent in this film, it's so disappointing that the writers were right . Don't waste a dime on developing a sensible plot because the hordes of fans will eat this crap up like it was a 5 star meal. Hence the 8.1 star rating which reflects a demographic with time on their hands and a studio with plenty of marketing budget.
On the bright side - the CGI is great. The sets are beautiful. There are some very funny moments. The cast still has some chemistry with each other. And I've seen movies that were much worse and unwatchable than this one. But I wouldn't be honest if I didn't give this a very generous 5 because of the horrendous, deficient plot. And after this film I'd have to say that I've about had enough with this series. We've heard the story, had some fun with the characters and it's clear that what was fun, fresh and original is what it should have been - a one film wonder leaving Hollywood to develop another story.
Without giving away the big reveal or true spoilers, I'll explain the problem that are evident throughout the entire film:
(1) Repeated jokes as if we're supposed to be warmed to it, e.g. how dumb and oblivious baby Groot is (except when he needs not to be.) Funny at the opening moment and gets more difficult to stomach as we make our way through.
(2) The fact that our heroes are never really in danger. They are always somehow able to avoid dangers of the most extreme kind for prolonged periods while they joke during the encounter and then you know they will be saved by some unknown force to be named shortly.
(3) The abject stupidity of supremely smart characters. Because we need those whose level of intelligence is off the charts to continue to do some really stupid or missing the obvious for a prolonged period of time but just enough for our heroes to have the time to do something to save themselves and the galaxy from certain destruction.
(4) The explanation of the villain's plan made absolutely no sense. It was the usual pseudo-brilliant but amorphous hogwash that only made sense when you were 5 years old in the world of make believe without having to think about whether there was any logic.
(5) Occasional product placement. Fedex anyone? It's one thing to have a "special moment" and another to believe we're too stupid to understand why it happened. And then there is Baby Groot who exists and will continue to exist solely for merchandising... Too cute to kill off. ;)