Very rewatchable (at least I think after one viewing so far) and well done. I think it balanced all the characters really well, leave one group—that being those of the Nidavellir side plot. It wasn't necessarily bad, but extremely detracted from the pacing and engagement; when there's stuff going down on Earth and Titan, I don't really care what Thor is doing to make a new hammer. This is the only plot/writing piece I had a ""major"" gripe with, though it really only impacts my own engagement and judgement of rewatchability. 
The one thing I'd really wanted to be good, though, was the score, and I felt extremely underwhelmed. The Avengers theme was used nicely, as were some of the motifs from Black Panther. Beyond those, though? I couldn't really pick any other themes or whatnot out—and for me, that was one of my most anticipated parts of this movie. I just wanted my Guardians of the Galaxy x Avengers x Spider-Man (Homecoming) x Doctor Strange x Black Panther theme mashup, okay? The only thing we really got was a little Black Panther x Avengers mixing (and a new, underwhelming Spider-Man theme). 
This doesn't really detract from the actual story etc, so it's not really as big a deal as I make it out to be, but you get the idea. All in all, I'd round it to about a 90%.

Also, why didn't Cap or any of the remaining people in Wakanda dissolve? Were they just the "half of humanity" left? If so, then... okay? I just wished we'd gotten some more explanation—or hell, just ended it at the finger snap.