I'm probably the only person who thinks this, but I think the lyrics are the best part of this. I know slant rhymes are a big turn off for some people, but I think there's a lot of creativity in their word choice and placement in a sentence (like rhyming "apple pie" with "pedophi-les" in the Girl Scout song), even if the rhymes aren't always perfect. It reminds me a lot of Tim Minchin, although I'd rank Minchin's work better than Eddie Perfect.
The worst part about Alex Brightman's performance is that he's trying to emulate Michael Keaton's gravelly voice too much, and it's hiding his higher register. Sophia Anne Caruso has a fantastic voice, and it was so shocking to find out she's only 17. The amount of control and range she has in her singing at such a young age is astounding.
The biggest problem with the songs is the same problem as the rest of the show: it's just way too much. Speaking as someone who loves complex, literate patter lyrics, there is too much info in each song given at too quick a clip even for me. There are songs in something like Hamilton that have a lot of information given to the audience a lot of info quickly as well, but there are also songs that are slower and give the audience a chance to breathe and parse through the text. Beetlejuice is like if every song in Hamilton was as fast as "Guns and Ships" or "Washington on Your Side".