The leads have a strong bond and a healthy, drama-free relationship. WRTW is very suitable as a show without misunderstandings and draggy triangles.

What starts with the promise of an interesting empire-level power conflict quickly shifts focus to palace intrigue in just one of the empire's six states, the type of endless (endlessly repetitive) squabbles in which the baddies can never be stopped for good.
(From other comments online, I've learned that this was added by the drama writers, and in the actual novel there are "only a few paragraphs" of the palace intrigue that makes up a big portion of the show.)

Since she's an excellent fighter, little Lusi doesn't always need to be rescued. Except when she needs to be rescued.
Most of the time she's just hungry, which is terribly unimaginative. (Eventually the writers forget that. Just like they regularly forget the whole 'falcon' technology.)

95% of the show, FL and especially ML are super mega smart. The only times one of the leads is in serious peril, it is because they devolve into truly moronic drama leads that make nonsensical decisions without consulting the other – otherwise the writers have no way of plausibly getting them into danger. Every time this happens (admittedly rarely), this is somewhere between disappointing and infuriating.

The villain(s) and the "token" plotline don't make a lot of sense to me. I don't know how much of that is because of Netflix's usual so-so translation quality, or how much stems from the drama adaption vs the original work.

I feel it must be mentioned how unpleasant Yang Yang's hairstyle he wears for most of the show is ("hair up" doesn't work with his face), and how poorly the matter of double identities is handled, especially with regards to revealing them.