There is no old feedback, so even though it was probably mentioned, I’ll do it again.
The one and only thing that makes me frustrated with WK is lack of explanation on synonyms. At level 3 there are about 3 ways given to say ‘girl’, and from what I know, those are not all the ways. So I get how WK works and what it’s purpose is, but as learning aid, this seriously hurts. Synonyms are not always so ‘same’ especially in languages like Japanese. There is a reason for and difference between those three ‘girls’. And yes, I can use google images (I think that’s the advice from TextFugu), or ask the community, or use any number of resources. But! WaniKani uses mnemonics, it forces us to remember kanji using very specific method, and it will only be harder to relearn that vocab later, when I actually have to face the subtle differences in meaning, tone or context.
I don’t know, maybe it’s problematic, maybe nobody wants to tackle that issue (as a lot of dictionaries don’t deal with it all that well) but this is the biggest problem I have with WK.