Fine for what it is

Rating: 6/10 (10 July 2018)

This is an entertaining movie - or perhaps I should say, Half-Movie, because it's clear they have a lot of mopping up to do in the next installment. I see that as the major flaw in this movie. A secondary, but related problem is that though all the other Marvel flicks were interconnected, they were still fully independent stand-alone films. This one is not. If you haven't seen the other Marvel movies, this one is not going to make a lick of sense.
I'm not going to rehash the flaws other reviewers have commented on, but I am wondering why more viewers aren't troubled by the fact that more than half the cast is over 40 and showing it - in some cases (Mark Ruffalo, Robert Downey, Jr.) really showing it. That's a major problem for actors portraying superheroes. Even Scarlett Johansson, who is not one of the over-40's, is starting to look like somebody's mom (just check out those close-up shots in the Wakanda fight), and Chris Pratt truly is "one sandwich away from fat" these days. Benedict Cumberbatch is safe for a while - Doctor Strange was always gaunt and graying.
The foregoing is not intended to be taken as age-discrimination, but rather as a possible answer to the question of why the movie ended as it did. Perhaps we'll soon be seeing a whole new cadre of Marvel Heroes...