What do you expect?
It is exactly what it is meant to be - just brainless song dance camp faux-emo theatre w very mehh story and loopholes gala. As such, not great but sure good enough.
The songs are far catchier and flow more naturally into the scenes than other musicals of this genre. Everyone sang better than expected - Meryl Streep's assured singing exceeds her shaky performance in Mamma Mia.
I don't particularly like James Corden either (but certainly not to the extent of his compatriot Piers Morgan whom I find a total yuckky loud ego fake), but to be fair I can't fault his good-enough performance here as with every cast member. Also, everyone else (except for Keegan-Michael Key who played it pleasantly 'normal', surprisingly) was camping it up so why shouldn't Corden? And his level of campiness suits the character and is by no means overdone. I don't know why so many people have an issue with him, when nobody seemed to bat an eyelid when Eric Stonestreet (who is totally straight also) camped it truly all the way up in Modern Family - why the double standard? Gays play straights, straights play gays - who cares as long as the performance suits the characters.
I recommend this good-enough brainless musical. Enjoy! 😊
