I caught The Flash at a weekday matinee and I found it to be a better film than I expected. I would give it a 7 out of 10. I enjoyed it more than Quantumania, but not as much as Guardians of the Galaxy Volume 3.
Lots of easter eggs for film and comics fans, and some funny lines that gave me a laugh. As others have said, Michael Keaton does a great job, and there are a number of callbacks to his Batman films that are neat without feeling too obvious as fan service.
I found the CGI to be about average. Without spoiling things, it does seem a bit hyperstylized around some effects in the film, which may be bad CGI or may be an artistic choice.
I am always a sucker for time travel/alternate universe stories, so I am predisposed to like movies like this, but my two friends who also saw it enjoyed it as well. Just anectdotal I know, but we all thought it was a good value.