It is safe to confess that Dylan Minnette and Brandon Flynn outgrew themselves in the last season and they perfectly portrayed the whole season. Especially in the very last episode. They both deserve the best there is.
SPILER ALERT!
The show completes what it has build itself on over the 4 seasons. To tell that there is a dark side in teen ages and it needs to be told. But it does not always get to be the best at it. Season 1 was based on the novel by the same name and it was tremendously great.
PERSONAL OPINION I think even though many disagree season 2 was good. On some level it didnt deliver like the previous season. That means should not justify the ways it is a told outcome of the show.
Season 3 is mess. The charactors and their supporting roles are so apart and out of sense. The show brings a new charactor who even though was portrayed perfectly does not fit to be a major decision maker for the season. The story's trigger is mind blowing but the show fails to be on the logical path and gets ahead of itself.
Unlike Ani who the smashes her to be Clay Jensen's Supporting role, there is another role which later on fits perfectly in the pack and this process happens slowly as possible. Charlie. A kind and caring person which puts Clay's shoes and is the kind person the whole group needs.
Season 4 fixes major mistakes. Impact of Ani, distant friendship between Clay and Tony, The person Alex needed in his life, Aftermath of Jess's decision to reveal her biggest secret they are all fixed in this season. The show brings in the brothership that can happen with people who are not related by blood. Clay happens to believe he needs help. They are all perfect angles of the season and the medium ending which insists on trying to be better is all a fit ending to the 4 seasons.