I really enjoyed it! I think it does a good job at recapturing the spirit of the originals; not just Alex Winter and Keanu Reeves slipping back into their roles, but that writers Chris Matheson and Ed Solomon penned something that really stays true to the characters and their upbeat, optimistic attitude. It would have been really easy to make a story about some aged 80s slackers into something cynical— which they show in the wedding scene— but they resist that, and instead fully embrace the eponymous duo in all their anachronistic flair, and let them be just two dudes who still have utmost confidence in themselves, each other and their music.
I liked that Amy Stoch (Missy) and Hal Landon Jr. (Chief Logan) reprised their roles— unlike William Sadler's Death, I don't think either of these characters are "iconic" fan favourites and they could have easily been left out; so to bring them back feels like they really were getting the band back together. It just makes it feel that bit more like a love letter.
The story itself did a pretty good job at drawing off of both previous films' ideas and meshing them into a cohesive whole, which is cool— the reason everyone goes to hell is pretty clever— though it does feel a little derivative at times, and I don't think it quite did as much with the future Bills and Teds as it could have. But the finale is worth it, turning what was always a bit of a gag into something actually meaningful.
It's not a classic like the first, nor a creative follow-up like the second, but it's a worthy follow-up and finale to the series, and stands out as one of the few long-gap sequels to really get it.