This post will look at the Arabic languages from the POV of how hard they are to learn for an English speaker.
Semitic languages such as Arabic and Hebrew are notoriously difficult to learn, and Arabic (especially MSA) tops many language learners’ lists as the hardest language they have ever attempted to learn. Although Semitic verbs are notoriously complex, the verbal system does have some advantages especially as compared to IE languages like Slavic. Unlike Slavic, Semitic verbs are not inflected for mood and there is no perfect or imperfect.
Arabic has some very irregular manners of noun declension, even in the plural. For instance, the word girls changes in an unpredictable way when you say one girl, two girls and three girls, and there are two different ways to say two girls depending on context. Two girls is marked with the dual, but different dual forms can be used. All languages with duals are relatively difficult for most speakers that lack a dual in their native language. However, the dual is predictable from the singular, so one might argue that you only need to learn how to say one girl and three girls.
Further, it is full of irregular plurals similar to octopus and octopi in English, whereas these forms are rare in English. With any given word, there might be 20 different ways to pluralize it, and there is no way to generalize a plural pattern from a singular pattern. In addition, many words have 2-3 ways of pluralizing them. Some messy Arab plurals:
kalb -> kilaab
qalb -> quluub
maktab -> makaatib
taalib -> tullaab
balad -> buldaan
When you say I love you to a man, you say it one way, and when you say it to a woman, you say it another way. On and on.
The Arabic writing system is exceeding difficult, and is more of the hardest to use of any on Earth. Soft vowels are omitted. You have to learn where to insert missing vowels, where to double consonants and which vowels to skip in the script. There are 28 different symbols in the alphabet and four different ways to write each symbol depending on its place in the word. Consonants are written in different ways depending on where they appear in a word. An h is written differently at the beginning of a word than you would write it at the end of a word. However, one simple aspect of it is that the medial form is always the same as the initial form. You need to learn not only Arabic words but also the grammar into to read Arabic.
Pronouns attach themselves to roots, and there are many different verb conjugation paradigms which simply have to be memorized. For instance, if a verb has a و, a ي, or a ء in its root, you need to memorize the patters of the derivations, and that is a good chunk of the conjugations right there. The system for measuring quantities is extremely confusing. The grammar has many odd rules that seem senseless. Unfortunately, most rules have exceptions, and it seems that the exceptions are more common than the rules themselves. Many people, including native speakers, complain about Arabic grammar.
Arabic does have case, but the system is rather simple.
The laryngeals, uvulars and glottalized sounds are hard for many foreigners to make and nearly impossible for them to get right. The ha’(ح ), qa (ق ) and غ sounds and the glottal stop in initial position give a lot of learners headaches.
Arabic is at least as idiomatic as French or English, so it order to speak it right you have to learn all of the expressionistic nuances.
One of the worst problems with Arabic is the dialects, which in many cases are separate languages altogether. If you learn Arabic, you often have to learn one of the dialects along with classical Arabic. All Arabic speakers speak both an Arabic dialect and Classical Arabic.
In some Arabic as a foreign language classes, even after 1 1/2 years, not one student could yet make a complete and proper sentence that was not memorized.
Adding weight to the commonly held belief that Arabic is hard to learn is research done in Germany in 2005 which showed that Turkish children learn their language at age 2-3, German children at age 4-5, but Arabic kids did not get Arabic until age 12.
Arabic has complex verbal agreement with the subject, masculine and feminine gender in nouns and adjectives, head-initial syntax and a serious restriction to forming compounds. If you come from a language that has similar nature, Arabic may be easier for you than it is for so many others. Its 3 vowel system makes for easy vowels.
MSA Arabic is rated 5, extremely difficult.
Arabic dialects are often somewhat easier to learn than MSA Arabic. At least in Lebanese and Egyptian Arabic, the very difficult q’ sound has been turned into a hamza or glottal stop which is an easier sound to make. Compared to MSA Arabic, the dialectal words tend to be shorter and easier to pronounce.
To attain anywhere near native speaker competency in Egyptian Arabic, you probably need to live in Egypt for 10 years, but Arabic speakers say that few if any second language learners ever come close to native competency. There is a huge vocabulary, and most words have a wealth of possible meanings.
Egyptian Arabic is rated 4.5, extremely difficult.
Moroccan Arabic is said to be particularly difficult, with much vowel elision in triconsonantal stems. In addition, all dialectal Arabic is plagued by irrational writing systems.
Moroccan Arabic is rated 4.5, extremely difficult.
Maltese is a strange language, basically a Maghrebi Arabic language (similar to Moroccan or Tunisian Arabic) that has very heavy influence from non-Arabic tongues. It shares the problem of Gaelic that often words look one way and are pronounced another. It has the common Semitic problem of difficult plurals. Although many plurals use common plural endings (-i, -iet, -ijiet, -at), others simply form the plural by having their last vowel dropped or adding an s (English borrowing). There’s no pattern, and you simply have to memorize which ones act which way. Maltese permits the consonant cluster spt, which is surely hard to pronounce.
On the other hand, Maltese has quite a bit of IE loans from Italian, Sicilian, Spanish, French and increasingly English. If you have knowledge of Romance languages, Maltese is going to be easier than most Arabic dialects.
Maltese is rated 4, very difficult.