I feel like the top reviews here really hit the nail on the head. But as a tl;dr it's a mid b-tier shounen, that is a good watch, but just falls short in basically every categories except seiyuus and music. It's a standard formula which had a fair execution, and an easy watch that doesn't require too much world building. It's not bad, but it really doesn't leave a mark in a season full of great animes and few years of shounen.
Is this a fun series?
Yes. I'll definitely be awaiting a second season.
Do I recommend you watch it?
You seem like you're in the market for a shounen if you stumble on this review. In which case yes.
Was it worth the buildup/hype from the community?
Questionable. Leaning on no, since the seed of doubt is there. I understand why people love the franchise, but combined with the hype and also saturation in 'demon/evil exorcists with a dorky, optimistic male lead' animes I don't really see the spark of originality. Had this been an unknown series (i.e. specifically not by MAPPA), it probably would have been rated higher, but neither MAPPA nor the characters delivered.
Voice Actors: 9. S tier voice actors; I don't think I could cast a better set.
OP/ED: 10. Really excellently curated and animated. They match the energy of each episode well.
Art & Animation: 6. The character designs are pretty great. You can see that both character design and OP/ED took a lot of care from the staff; and for that they deserve way higher, but the obnoxiously slow turns and also lack of detail on the non-action scenes really did a huge disservice to the show. Specifically Kobeni's scene with the car speeding away will easily be in my mind as one of the top worse animations ever, but maybe it was an intentional and stylistic choice.
Although I guess with every high quality mv level ending though, that time had to be taken from somewhere.
Characters: 6 - I feel like in the first episode, I really loved the diversity of personalities, but none of them really seem attach worthy-- Denji included.
Plot: 7 - It's a bit average, but executed without complaint. Our resident noob Denji might be a simple person, but he improves and struggles at a reasonable pace.
Final Score: 7.55559. Round up if your main genre is shounens, -- it's a 7 otherwise. The saving grace of the show, which I desperately want to chuck in the 'average' save your time bucket is the introduction of a lot of great voice actors who bring each character to life so well.