Or rather, to quote the exact prompt: Frustrating things about English that you think German does better. And vice versa.

Well, first of all, English is far easier to learn, which is why I'm lucky to have German as my native language. English has this nice gender neutral universal "the", whereas German is gender specific with its nouns: a word is either a der, a die, or a das. Which means if you learn it, you have learn two words for one, effectively. (Mark Twain ranted about this and other problems when learning German to great hilarity.) Also, if you write in English, you can disguise the gender of a person for dramatic revelatory effect if necessary, which I needed to in the fifth of the Five Things Which Never Happened To Warren. You can't do that in German.

On the other hand, German allows you to signal various degrees of closeness and distance in relationships in a way English can't, simply because we have "Du" and "Sie" as modes of address, and you have abandoned "thou". Mind you, in the internet - say, Facebook - it's by now customary to call everyone "du" these days, but outside of the virtual world, you call adult strangers "Sie". Also people older than yourself unless they're related or offer the "Du". Offering "du" outside of the virtual world isn't something you do immediately, or at least I don't, because to me there is a fakeness about this, presumating an instant "buddy buddy" relationship which doesn't exist (yet).

(Another thing: I'm 43, but when I meet some of my former teachers, who knew me in school, I would never call them "Du" or address them by their first name, which is why I always had an amused jolt of recognition when Jesse Pinkman kept calling his former chemistry teacher "Mr. White" through five seasons of Breaking Bad.)

There are words in English which don't have a German equivalent, like "haunting", and anything derived from "to haunt", and I love that word; conversely, there are some German words which don't exist in English, though you've generously adopted them, like "Schadenfreude", Gemütlichkeit", "Weltschmerz", "Lausbub", or the ever popular "Angst". It fascinates me to find words in either language without an exact equivalent, as it always makes me wonder why that is, and whether knowing both languages changes one's thinking.

Something very frustrating in English which isn't the fault of English: we have by now words in German which are sort of English only they aren't, they were made up, and if you switch into English you have to remember that. Like "Handy", which means "mobile phone". And there are words which mean something completely different yet sound very similar. A "slip" in German means panties, whereas slippers in English are what we'd call "Pantoffel". "Chips" in German means "crisps" in British English, because "chips" in British English means french fries (which is "Pommes Frittes" in German because the French introduced them to us first).

Lastly: there is sex. I'm a gen writer mostly anyway, but I have written the occasional sex scene. Which for some reasons feels far more awkward to do in German than in English. Ditto, by the way, for reading sex scenes in either language. With exceptions, always. But we can't all be Goethe writing the Römische Elegien and celebrating des knarrenden Bettes lieblichen Ton. Mind you, sex scenes in either language often read involuntarily absurd because they're lacking a sense of humour and instead go for gymnastic competitions, but even though - they're easier for me in English.

Rant of the day: English is not my native language, but I think I speak it reasonably well. So watch me feeling entitled to be irritated-to-disgusted by the frequent use of expressions like "rapey", "rape time", "eye rape" etc. in a positive manner, because if "rape" means anything other than "sex forced on one non-consenting partner", my dictionary has not told me so. And using the term in a joking manner (especially when the writer/speaker actually means "checking someone out who is also attracted to you") belittles the horror of the real thing. Just as bad: "pedo" for someone other than "person who likes sex with children". Considering, say, a 17 or 18 years old teenager (especially if it's a fictional one) sexually attractive has nothing to do with pedophilia, people.

(...I wrote my rant about the use of "Nazi" in English in combination with Christmas, feminism, grammar etc. elsewhere already, I think.)