Classic Monk with an exceptionally moving ending and a few surprises, i.e., looking through the credits, the murder weapon, etc. Unfortunately, there are a few "non-surprises" as well which seem beneath the respective character's intellect, i.e., determining who the killer is, why a few props were out of place, etc.
However, classic Monk is classic.
To paraphrase, half the joy of getting there is the journey, or something like that. Each character is well fleshed out, back stories are plausible, everyone comes together quite well after moving on for more than 13 years, and the requisite catchphrases are present and accounted for. It is possible, but most likely problematic, to understand the intricacies of the series without having watching at least some of it which can be confusing. The overarching theme depicting Monk's battle with a decision he seems to have made and how the murder that needs solving may alter that decision because of its overtly personal nature is more than engaging. The aforementioned surprise ending needs no explanation and is satisfying for all.
Ultimately, for the uninitiated, you can easily become a fan by simply enjoying the journey, and for the rest of us-well, we get to enjoy both the conclusion and the journey.