I can certainly see where he is coming from. Season 1 was all about developing characters, finding purpose and forming relationships. Great scenery, lots of action, easy to enjoy.
Season 2 has more struggles with the established characters and ends on a brutal cliff hanger. Since its mostly based on the book 'Blood of Elves' the story line also pivots to include the elves struggle as well. And the elves played a very little role in Season 1, so kind of a big switch.
I did read some people's complaint was Season 2 focused too much on setting up season 3 and not enough vision for the story at present.
I personally enjoyed it from the very beginning of Episode 1.
Also, the time spent at the 'Witcher's Keep', Kaer Morhen , without giving away too many spoilers, we get to learn a lot more about the Witcher history.
Season 3 is rumored to be mostly based on the more popular of the books, Time of Contempt. Also suppose to reveal more about the 'Wild Hunt'. Sign me up.
It sounds like they are fantastic reads, I am looking forward to starting the series.
Another possibility was your friend was disappointed not seeing Yennifer nude, unlike in season 1. In which case, I can also understand✌️😉
But saying Season 2 was awful would be slightly over dramatic.