I'll keep it brief: It isn't fun and Mysterio is both the best and worst part. The movie is missing that Marvel charm, yet it devolves into mindless action faster and messier than most of the MCU. There are many smaller fight scenes rather than just one big one--so when you're in the middle of the actually fun character comedy a fight scene might randomly start and distract from the high school antics--and the choreography is messy to the point where it's hard to focus on what's happening. Even worse, there's a point where Mysterio even points out that the choreography is awful (light on spoilers, but he is clearly saying the choreography itself is poor; there's no other meaning). Mysterio's goals are relatable similarly to The Vulture's, but his plan is insanely crazy, stupid, and impossible. It directly mocks several fan theories and those who theorized them (or those who, like me, gave them a passing glance and thought "Maybe. Anything's possible in the MCU."). Jake Gyllenhaal is lovable to watch when he's playing nice, but when the plot ramps up it seems like he becomes less in-tune with his character. There's a weird sense of remorse he has for a character who has lines about being alright with child murder. Is he evil or just chaotic? The Vulture worked because he had a relatable goal and relatable feelings when it came to who had to die and what price had to be paid. Mysterio is relatable until he becomes nearly as indiscriminately murderous as Thanos.
There is decent character comedy, and MJ is given more development, but everyone else feels plainer than before. There are several romance subplots which are given little time, and you always feel out of the loop. Perhaps it's because Peter is questioning about if he should be Spiderman or Peter, but it feels wonky regardless. There's a meaningful plot about identity and gullibility but the characters feel more dense than before so its difficult to really dive into their heads.
Even as an MCU movie its a hard sell, but it's surely going to be so relevant to Phase 4 that if you have interest in post-Endgame Marvel then its probably a must-watch. As a movie though, it features poor action and a nonsensical villain plan, and the good high school antics comedy mixes harshly with the main plot. I would argue it's around the same level of quality as Raimi's Spiderman 3.