The real hard part of Arabic is the morphology. It's "irregular", both in the human sense that there's all sorts of horrible exceptions to ridiculous numbers of

The real hard part of Arabic is the morphology. It's "irregular", both in the human sense that there's all sorts of horrible exceptions to ridiculous numbers of rules, and in the compsci sense that you cannot recognise/produce the inflected forms of nouns and verbs using a finite state automaton/transducer. (Though, that's true for all the Afroasiatic languages including Amharic, Hebrew, and Hausa, but the FSI claims those are only "Level II" languages). Also IMO Arabic phonology is a lot harder than either Chinese or Korean. (Chinese has tones, Korean has tensed versions of the same consonants we have in English, but Arabic has the pharyngeal and glottal consonants, completely unlike anything in English). On the other hand, Georgian's worse. Finally, if you take Arabic in a school, they're going to teach you Modern Standard Arabic AKA fusha, which is basically in the same position that Latin was in 14th-century Europe: useful if you like to do nothing but read, useless if you actually want to understand what people are saying.