Tony Shalhoub assumes center stage here for the season "finale" (or half-season finale, or whatever USA is billing these things as) in what is clearly a performance intended to garner him an Emmy performance.
Shalhoub basically plays three different characters here. First is his normal "Monk" persona. We see only a little of that here - a bit at he beginning after he leaves Kroger's office and at the end when he solves the case. It's well done as always, particularly when he "resets" as it were and figures out the clue at the apartment.
Then there's "beaten" Monk. We've never seen Monk like this before - desperate and self-hating at his own condition. Unfortunately, this is rather out of nowhere - Monk didn't seem this desperate in the preceding episode so this kind of comes out of nowhere (and apparently disappears just in time for the end of the episode). Oddly, this is similar to something similar on the other show I review - Justice League, with Wonder Woman. Suddenly she has anger-management issues. No hint of it before, and it's gone by the end of the episode. It's a flimsy excuse to hang a extreme characterization on so that the character can "fix" it in one nice neat 21- or 42-minute package. Couldn't they give us 30 seconds to give us a scene of Monk's OCD making his life miserable? A scene like his being unable to play his clarinet with Willie Nelson because someone used the mouthpiece (in Red-Headed Stranger)?
And there's "The Monk." Obnoxious, grating, the exact opposite of the self-hating Monk - this one is the self-focused version that doesn't think of anyone but himself. Even at the end he goes back to "normal Monk" out of self-concern - he can't make contact with Trudy any more and he's shunned. There's no indication that he finally realizes his lack of caring toward Stottlemeyer and the others. This selfishness isn't obvious, but it tends to mute the tragedy at the end.
Giving Tony Shalhoub all this to do suggests this'll be the episode the producers submit to the Emmy category. Which seems a little odd that they have such a "engineered" episode to highlight Shalhoub given he's capable of winning Emmys without this kind of thing.
The lack of subtlety seems a little odd given that one of the writers was Tom Scharpling, who has done some of the more humorous and touching episodes of the series - Red-Headed Stranger (one of the top vote-getters in the preceding marathon/poll) and T.V. Star. Maybe it's the bad influence of Chuck Sklar, doing his first Monk script and whose previous works include such subtle fair as The Michael Richards Show. This episode just seemed very, very heavy-handed.
Giving us Melora Hardin as Trudy again seems to be a case of trying to force her on us as if they can convince us to accept the new actress. We haven't seen Monk doing his pillow-ritual before and it's a pretty obvious gimmick to show Monk's loss.
Having Monk "lose" Trudy and going back to normal to regain her also means he isn't doing it because of his friends. Which is a shame because all three of the regulars get a chance to shine here after being omitted for whatever reasons from the previous episode. Disher does best - this is the first episode this season where he isn't a near-complete buffoon. Yes, his claiming Stottlemeyer is his "partner" is a bit overboard but reasonable given the circumstances.
Sharona actually acts like a nurse, and in theory you'd think there'd be some kind of issue between her and Kroger. And...is Kroger supposed to be handing out medicine? Or doing so and then not checking up on his patient for the rest of the episode? They make out Kroger to be an incompetent just to come up with a way to "cure" Monk temporarily.
Stottlemeyer doesn't have a lot to do other then get shot in a fairly serious moment - otherwise he just does "horrified reaction" a bit. But there's a comforting interaction between the three of them that helps to stabilize the audience against the erratic New Monk.
The mystery isn't much, the murderer hardly seems worth Monk's efforts even if he were cured, and how did the police miss the "big clue" while powdering for fingerprints? We also get a variant denouement of the mystery, as Monk delivers it from a speeding car.
Overall, in a season where the worst episodes were those early ones intent on giving Tony Shalhoub his acting "moment," Takes His Medicine basically spins his "moment" out into a full episode. If you thought "Lobby...lobby...lobby..." (Blackout) or Stottlemeyer jumping up and down to taunt a monkey (Panic Room) was the height of hilarity, then you'll love this one. Otherwise sit back and enjoy the strong steady performance of the other regulars and the subtle ease with which Shalhoub does "normal Monk" ("He's my captain too" says more then a dozen overbearing scenes) without the overacting of his other two incarnations here.