I saw this earlier in the week. Went with a big group (9 altogether) and opinions ranged from 'enjoyed it a lot' to 'absolutely loved it'. Thought that Sam Tutty was great and was really impressed to see that he won a Tony for playing Evan Hansen, about as different a character as humanly possible. I thought the female lead, whose name I cannot remember right this minute (no programs) was also very good.
If the issue that prior posters are referring to has to do with a past assignation on the part of the female character, that was almost required to make any sense out of the degree to which she was a gofer, yet wasn't invited to the wedding.
If it had to do with the real invitation, that did not work for me -- didn't seem like the time or the place to bring the issue out into the open. I did not let that illogic keep me from enjoying the show.
The only thing I will add is that, as with almost every other musical the last few seasons, the music did not stand out. It was not bad,
I doubt that this would succeed on Broadway -- it is very slight -- but I would agree that a larger off-Broadway theatre might be the way to go.