" Season 3 is widely regarded as a pivotal turning point in the series, characterized by the jarring mid-season transition from Monk’s original assistant, Sharona Fleming, to his long-term partner, Natalie Teeger. While critics generally agree that the show maintained its charm and high production value, many fans and long-term viewers note a shift toward more overtly comedic and sometimes "cartoonish" behavior from the titular character. The defining element of Season 3 is the departure of Bitty Schram and the introduction of Traylor Howard
For new viewers looking to dive in, here is the best approach: Monk - Season 3