There a LOT of plot holes and issues with the handling of time travel BUT...WHO CARES!?!?! That was the single greatest fan service movie of all time, it was amazing fun the entire time, there were clever quips at every turn but it never felt forced or overdone. I loved it. AVENGERS.....ASSEMBLE. You have to be heartless to not fall out of your chair cap dropped that line.
The best thing the MCU has done has been creating serious moments without taking themselves too seriously. Like rocket saying 'hes pretty good at that' after caps speech. And this movie delivered on that. Lot of heavy scenes done well, but never taking themselves too seriously.
It delivered on what i wanted to see anyway. Fun, callbacks, intense, great!