Short answer: German is ranked a Category II language by the US Foreign Service Institute, meaning medium difficulty for native English speakers — harder than Spanish or Dutch, but nowhere near as hard as Mandarin, Arabic, or Japanese. Reaching professional working proficiency is generally estimated at around 750 hours of study, roughly double what a Category I language like Spanish takes.
What makes it easier than people expect: English and German are both Germanic languages, so they share a common ancestor and a surprising amount of everyday vocabulary — Haus/house, Wasser/water, Buch/book, trinken/drink. You're not starting from zero the way you would with an unrelated language family. German also uses the same Latin alphabet as English (plus ä, ö, ü, and ß), and its spelling is far more consistent than English's — once you learn the pronunciation rules, you can read almost any German word aloud correctly on the first try.
What actually makes it hard: three grammatical genders (der, die, das) that you generally have to memorize per noun, four grammatical cases that change articles and endings depending on a word's role in the sentence, and word order rules that push the verb to the very end in clauses starting with weil, dass, or wenn. None of this is intuitive if your only reference point is English, which dropped most of its case system centuries ago.
The honest reframe: German is hard to master perfectly, but not hard to start speaking. Ordering food, introducing yourself, asking directions, and having a basic conversation are all realistic within your first few weeks of focused study — long before you've untangled every case ending. Fluency and "technically correct in every sentence" are two very different goals, and conflating them is what makes German feel more intimidating than it needs to be at the start.
The fastest way past the genuinely hard parts (cases, word order, gender) isn't more grammar tables — it's real conversation with someone who corrects you in the moment. A tutor catching "in dem Auto" versus "in das Auto" as you say it teaches the rule far faster than reading about the accusative/dative distinction in isolation.
