Season 1 was strong. The pacing, action, and plot-twists were good. The changes from the comic (namely that The Boys did not have powers) was handled well.
The quality dropped off considerably in Season 2. The emphasis turned from plot to character development. Unfortunately, the character development wasn't compelling enough to overcome the lack of suspense and slow pacing. There were maybe five episodes worth of plot spread out over eight episodes. The cliffhangers from Season One were quickly glossed over and forgotten. Instead of exploring those interesting plot lines, the writers gave us a lame soap opera and a tepid mystery that served to slowly build up to a lame final boss battle. Although Stormfront's "political" plot line was treated with complete earnestness and presumed topicality, it was a cartoonish and painfully on the nose. It seems like they needed a villain against whom both the Boys and Seven could fight, because they've decided that the Seven are also protagonists.
It was obvious that the third season had already been commissioned as the writers had to both maintain the status quo and give sufficient airtime for all the contracted actors, even if their characters were no longer needed for the plot. This series shouldn't have a status quo.
There has been much discussion about the decision to gender-switch Stillwell and Stormfront from their comic book counterparts. Luckily, Elisabeth Shue and Aya Cash gave great performances. However, before you feminists rejoice, consider this: both of these characters were made female in order to provide a romantic interest to Homelander. I argue the decision had nothing to do with female representation, but rather served the dramatic needs of a male character, and so was no win for feminism at all.
The setup for Season 3 puts the Boys closer to the original setup in the comics, so I am mildly optimistic about the next season, although the "big villain", again, is being set up to be an antagonist against both the Boys and the Seven.