These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Angst? What Angst?: It is commented on that Misa seems to have taken being tied up and interrogated pretty well, and that, as Erin brings up in her "The Reason You Suck" Speech, L doesn't express considerable conflict over the many lives that have been destroyed by this case, including his own. This is subverted for both cases by the end, though.
Draco in Leather Pants: Light and Misa are looked at more sympathetically despite their actions, even when they're found out. This trope is also played with for L. Then again, the narrator is prone to Sympathy for the Devil, even towards the nastiest characters. This trope along with Ron the Death Eater are zig-zagged with each other.
Foe Yay: Between Light and L, L and Misa, Misa and Erin, and Misa and Higuchi.
Ho Yay: Between Light and L naturally, what with their always being together...
Also, Erin and Misa. In the background, Rem and Misa.
L's actions towards the end are treated as crossing over this, at least due to intention rather than the action in itself. After Erin overhears Light and Misa discuss their plans, she tells L about it in secret. Without the task force's knowledge, he has Wedy break into Misa's apartment to steal her notebook that she'd dug up, and replaces it with a counterfeit made by Watari. He has the deaths covered on the news channels to make it seem as though Misa's still killing criminals. Then, to give himself immunity to the Death Note, he writes his own name in Misa's notebook and gives himself 23 days. He uses this also to manipulate Soichiro and the task force into going along with the rest of his plan, which includes pretending to test the 13-day rule in the notebook using two death-row inmates and luring Misa back into a trap. Not knowing any of this, Erin tries to destroy the notebooks (despite one of the fake rules) and free Light and Misa from their influence, only to have L tackle and knock her out so she can't interfere. The reason this is considered his MEH is because, at least according to Erin, he was more concerned with exposing the two Kiras and solving the case rather than actually saving anyone. Letting her destroy the notebooks would be destroying the evidence, essentially letting Kira get away for good. He doesn't deny it when she calls him out on it, either...
Narm / Narm Charm: Erin has a rather wacky way of describing things; she has a penchant for being both hilarious and serious at almost the same time in both her narration and in-story reactions. Combine that with a series that already has its fair share of Narm...
Misa can get pretty narmy herself, in the eyes of some.
Erin threatens to towel-snap L if he doesn't talk after they come out of the rain after she hears Watari talk to L over the phone about "the plan."
Erin: You dumb monkey, you're dog meat if you go through with this.
(…Did I just call L a dumb monkey?)
Ryuk showing up out of nowhere just to write Light's name in his notebook, coupled with Light's reaction to it, could be seen as narmy to some readers.
L giving Erin (who's coming off medication he had given her to help her calm down) a noogie in the aftermath of Light's death, after all the times she had given him noogies. Poignant to some, kinda funny to others.
Speaking of, Light and Misa try to kill Erin, an innocent girl who confronts them just as Light is in the process of writing his own father's name in what he thinks is Misa's notebook. It's assumed that Light might have gone on to kill everyone else afterwards had he not been thwarted. From their standpoint, it was probably justified, but still...
Actually, it might be accurate to say that for L, Light and Misa, this trope along with Draco in Leather Pants are zig-zagged with each other.