If you're a fan of the original Bill & Ted movies, I recommend not watching 'Face the Music' as it ruins the tone of the originals.
***SPOILERS WARNING***
As much as I love Keanu Reeves, it feels like the acting falls flat. The two main actors try to recreate their original characters exactly the same (only older), but something about the performance just doesn't feel the same as in the originals.
Their two daughters are identical recreations of their fathers with the exception that they don't actually make any music; they only listen to music. Predictably, and also disappointingly, they make the daughters the heroes of the story at the end as they are tasked with putting together the song that saves all of time and space. Although they tried to recreate the feel of the original movies (many of the tropes are literally taken from the original movies) it just didn't have that same magic that the originals did.
Also, as others have pointed out, Rufus had a brief cameo as a hologram but didn't add anything to the story at all. They could have left him out entirely and it would have been the same movie.
Throw in a dim-witted robot that looks like a giant iPhone and you've got yourself 'Face the Music.'