I agree with you that the first movie is way better.I love the first movie. It's one of those few super-hero movies that I have seen several times and still enjoyed at pretty much the same level at repetive viewings. This movie, sadly not so much.
Lets start with the villain as he proclaims himslef to be Miles nemesis. Spot is still played up for laughs and they don't seem to want to go beyond the goofiness of the character, at least not in this movie. He was so inconsequential to my enjoyment of the movie I actually forgot he was in it when we got to the second half.
Then we get Miguel as an antagonist. Poor Miguel this was not the showcase I wanted for you. Not only are you removed from much of how your personality usually is by being so rage fueled but they also make you job for Miles. Miguel was ok in the start when he still was conflicted. But the more the movie went on he was animated as some beserker thrasing his way through the set. It made it abundantly clear that they where trying to set up some "Miles is right" narrative that didn't jib that well.
The more Miles is right the less competent everyone else looks. It's fine with a large organisation in a movie where the boss is missguided by emotions to miss something that the hero sees. Or that hope and standing up for yourself fighting for something you belive in can save the day. Those are hero troupes. It's just that the organisation is made up of AU Spider-men. It both makes more sense that they know more then Miles and that Miles must learn some hard truth for the movie to have a more fulfilling theme.
So I found Miles and his unwillingness to listen and think beyond himself, as it is with these sci-fi concepts like multiverse, to be in character but not in line with the hero edit the movie gave him. I want the movie to show us that Miles can't just fix this without sacrifice. I just don't felt the movie was showing us the ambiguity of the different sides. They more or less gave Miles the hero edit and Miguel the villain edit. So far the evidence is pointing towards Miles risking his whole universe and as a consequence of that the whole multiverse is in line. I can see why people want to believe that it might work but the evidence isn't pointing towards that and therefore they need to act against him. At least detain him.
Now we are seen seeds of doubt in anomalies and Captain or not. It's just that so many Spider-men and earlier canon breaking points can't just all be hinging on Miguel and his theories. It makes for a less enjoyable story and movie if so.
Many of these new Spider-men where reduced to jokes. Ben Reilly the most profolictic victim. I felt the first movie never treated it's spider-men like this. Noir could easily have been just a joke but he wasn't. Even Spider-ham, who is a living joke, wasn't treated like a joke. For me this took away from the emotional core of the movie. It made me care less.
Hobie was a bit grating. Jess has a motorcycle. Mumbattan Spider-man was annoying, just plain annoying. It felt like Gwen and Peter had to carrry a heavier load to balance that out. Thankfully Peter has Mayday who just makes you smile.
It's still an ok movie it's just compared to the first it pales.
Score: 7-8/10