I was really pleased with this season and the finale. They've been building to Lena finding out her identity for such a long time that it coming from Lex was very painful. I would put either this or the Legends finale as my favorite one in this season of Arrowverse shows. The Flash finale didn't do a lot for me, and I disconnected from Arrow so hard this season that I couldn't even pay attention to what was going on in the show for the past several episodes.
The lowlight for me was definitely killing off Manchester like that. I thought at the very least his death would have had more of a lasting impact on J'onn, but nope, just one episode of vision quest and he was totally ok with killing a man in cold blood. And this may be petty but it really rubbed me the wrong way that while Manchester's methods were wrong, he was mostly on the good side, or at least had good ideals, and he was killed off with little remorse, but Lockwood, the guy with wrong methods AND wrong ideals just gets sent to prison.
Overall I did really enjoy the season as a whole though, especially when Lex entered the fray and everything started coming together. I liked all the additions to the cast, and if they could just find a way to make Jimmy work they'd really have something good going.