Japanese is an example of hard. Any creole is an example of easy. Then things with big phonemic inventories are gonna pose challenges for anyone. Large numbers of irregular verbs make a language hard. There's different ways to be hard: phonology, grammar, etc., and some have all of them.

[–] Erika3sis@hexbear.net 1 points 3 weeks ago

I would say that the difficulty of most any language has a lot to do with one's own background and interests, or one's goals and expectations and motivation and learning style, because if you were to ask me if Japanese was hard I would say "not really". I generally say that learning a language involves two main categories of skills — comprehension and production — and there are a lot of discrete skills within these categories which will be of different relevance or different difficulty for different people.