Hoo boy, I'm glad I didn't watch the trailers - they give too damn much away, as usual. Anyhow, my take:
As good as Avengers: Civil War is - and it's quite good - it's also inessential in much the same way Week of Ultron was. Enter Spidey and Panther, back to sleep for Barnes and maybe Rhodey's fighting days are done, but apart from that, things end up for our heroes more or less the place they start. Sure, the Avengers are on pause, but they'll be back for the Thanos fight as surely as Supes will be back for Justice League, and neither movie bothers to hide that. And while I feel for Bucky, after three movies, he's still little more than a blank. I kept expecting him to offer to let Tony kill him, particularly after he noted that, at fault or not, he did do the stuff he did. (I also expected Pepper to call and tell them all to cut their sh*t out.)
The Russo Brothers have said they couldn't bear to draft a version of this movie without Spidey. To which I reply: huh? Sure, he was lots of fun, but he could absolutely have been cut, and the movie's narrative and themes would be virtually unchanged; their wasn't any hint of an enhanced registration act directly affecting him. Similarly, though the Nigeria battle was cool, it served barely any story purpose. Also: the UN invites a psychologist to interrogate the world's most important prison, and not a single person notices he looks nothing like he's supposed to... okay, fine, that's dumb, but I'll play along. But why did the Stark hit require defrosting the Winter Soldier?! They were apparently unarmed; any two-bit clown could have taken them out!
IIRC, Feige has promised that Thor: Ragnarok will shake up the MCU Phase 3 status quo they way The Winter Soldier stirred up Phase 2, and with Loki on the throne in Asgard, and the action going cosmic, that certainly makes sense. That may have been my most anticipated non-Infiinity War flick of the phase, as I'm a big Dark World booster, and this movie does nothing to change that.
To be clear, Civil War is far, far better than BvS, and it's a fine flick. But it's not great on the level of Days of Future Past, and it's not as good as The Avengers either; though I appreciated the novel (for the MCU) lack of a massive action climax, it's yet another Marvel Studios movie without a really hissable or memorable villain. I'll give it a
B+, and hope Apocalypse will, like First Class and DoFP, be even better. (That said, this does make Marvel Studios 13 for 13, an absolutely amazing run with no signs of letting up.)
Pretty much agree with you (may be the first time

I gave it a B and it adapted the awesome Civil War storyline very well to the MCU (they couldn't obviously include the whole Marvel lineup in the movie so they made the second best thing).
Chadwick Bozeman was awesome as T'Challa and his fighting skill is impressive, very fast and fluid.. like a Panther (see what i did there? No? Whatever!). Small easter egg was his suit effortlessly withstanding heavy machine gun fire and him not budging an inch.. guess what the suit incorporates

Spidey.. for the comparately short time he was in there he was awesome. Tom Holland is a remarkable good fit for the role, even after Tobey Maguire who really brought the role to life in the movies (at least the first two). I'll be definitely seeing his solo movie and have high expectations now.. more proof that all Marvel characters should be returned to Marvel because they obviously get their own characters and seemingly effortlesly make them better what other have tried in multiple movies (imagine their take on the Fantastic Four if they had the chance and would be willing).
Civil War itself.. a seamless continuation of the entire MCU story and it was so integrated that it felt more like Avengers 2.5 than a pure Cap movie which may be the reason i "only" gave it a B but when you use the Civil War storyline you can't make it Cap only but it's not too bad because it is a Cap centric storyline and the crumbling friendship with Tony was quite well done i think (nice "I could do this all day" throwback but i would have even liked the scene from the comics better where Cap is standing all torn up yelling "I'm not going down to a pampered punk like you" but MCU Steve is not that crass).
The other detractors are minor.. as Gaith has said Black Panther and Spiderman are really not essential to the story but have obviously been included as setup for future movies which is ok but it kinda also distracts needlessly.. i think Cap 3 is the longest movie and could have used some more editing but then again i know jack shit about the realities of movie making and movie decisions

All considered it is a very good and entertaining movie, full of easter eggs for comic book fans and for the general audience and engaging storyline however it kind of still won't make it to my Top 3 MCU movies (The Avengers, Cap 2, Guardians of the Galaxy in that order) but it may be a contender for Top 5 at least.