People did lose their shit over season 2, in various ways. Irene Adler is a really divisive character from what little fandom discussion I've seen. (I generally avoid fandom at large for... basically everything.) In my experience, half of everyone loves her and the other half thinks she was handled really badly. I like her, personally, though I see some of the complaining points.

I've been enjoying season 4, but I didn't bring a lot of expectations, and you just reminded me that I haven't seen the last episode of it, which I think is out now. I'll have to watch that before I come to any conclusions.