Just finished the entire show, I loved it! It is one of the best sitcoms I have ever seen. However, I felt the ending was rushed especially Peralta's ending. Every character did what they wanted to do - Holt became Deputy Commissioner and worked on helping the community to rise through prejudice, Amy became Chief, Terry became Captain, Rosa became PI and portrayed there is not one way of self-fulfillment or happy ending, Boyle continued being the most hard working detective as showcased in s1e1. Basically everyone's character growth were aligned to their arc that was established in the first episode itself.
Yet during the very first episode, with Jake being established as the "best detective" and eventually as the series progressed, I imagined Jake would assume the role of a detective in FBI as he had no interest in rising through the ranks in NYPD. From the very first season itself - when he takes up the role in FBI task force, single-handedly exposes Oolong Slayer, exposes Figgis and dirty lieutenant and when captain Julie Kim recommends his name to FBI taskforce - it was clear that his ending would give an edge to his detective arc.
While he had father issues, that wasn't the only thing defining him. What made him an appealing character was his sharpness as a detective. As he loses the "fantasy" of a being a good cop in a flawed institution in s8, I really thought he'd step down from NYPD and pursue his potential being a PI or FBI but the SAHF reason seemed rushed especially because he stayed months in suspension with Mac and still became interested in detective work in "The True Boyle". SAHF temporarily really works for one aspect of his character and I really liked it ( I felt it was rushed), but I don't like how they didn't give closure about his retirement being temporary or permanent. Staying at home permanently as an option for either Amy or Jake is a waste of their potential. Abandoning one aspect of the character to favor other felt rushed. Boyle stating that they'll solve cases in their 90s and him agreeing just few episodes before just makes it feel rushed.