This show was great! I have never come across a superhero show like this one. It stands out from all the other Arrowverse shows. My favorite seasons are 1, 2, and 4. I think season 3, 5, and 7 are the worst seasons. The rest are just okay.
Season 3 messed up in introducing Savitar. I don't think anybody like the twist on the identity of Savitar. They did not think of a very creative idea into how Savitar's version of the show should be like.
The plotline of season 5 was poorly written. They messed up on Thawne's part. I love seeing the reverse-flash, but there were a lot of plot holes into how he was mixed up to what was going on. They didn't make much a connection to Thawne with Cicada, and it got more messed up when they tried to introduce Godspeed to the whole thing.
For season 7, there was just too much change to the show that I just didn't like. Ralph was gone, Cisco was leaving, Joe is no longer a cop, and there were no more Harrison Wells. The season was divided into three parts that weren't interesting. The main villain was taken down too easy. The story of the forces were just so complicated. They messed up on introducing Godspeed. He wasn't the big bad villain that I was expecting him to be. Pretty much after season 7, nobody became concern about the flash's story afterwards. I could tell from then on that the show wasn't going to be as good as it was in the beginning.