What I'm proposing is to list which are the difficulties in learning it (weird sounds, particular properties of words, availability of materials), and what are some easier points that sort of counter-balance it. No numbers at all.
Some quickly written sample:
Standard Arabic's noun morphology is difficult in that it distinguishes singular, dual and plural number, for both masculine and feminine gender, three cases (nominative, accusative, and genitive), and definiteness (definite and construct state, and indefinite). All written in one word.
However, the dual is incredibly easy to derivate from the singular: Simply take the stem, and add -āni for nominative case, and -ayni for accusative and genitive case. The plural still has to be learned along with the singular though, what is usually called "broken" plural: كتاب kitābun "book", كتب kutubun "books; طبل ṭablun "drum", طبول ṭubūlun "drums"; شكل šaklun "shape", أشكال 'aškālun "shapes". For adjective agreement, you can consider the masculine singular to be the basic form of the adjective, and knowing a very short list of suffixes you can derivate all the the other forms. A good number of adjectives also have broken plurals like nouns though. Arabic is also special in that in the plural, all non-human nouns are always feminine singular, so you would refer to a group of baskets as "she".
You can easily guess if a word has feminine gender. In the singular, they usually end in ـة -atu(n) -ata(n) -ati(n), ـاء -ā'u -ā'a; in the dual, in ـتان -atāni, ـتين -atayni; in the plural, ـات -ātun, -ātin.
The cases, unlike other languages like German or Russian, are amusingly simple, consisting of only a handful of suffixes. There are two noun/adjective declensions, but they only difference is if you add an -n in the singular or not. Now you must only concentrate on learning which case is used where. Definiteness is marked by a combination of case and the article al-, and remember that adjectives also carry the article when agreeing! أطفال شطر 'aṭfālun šuṭṭarun "skillful children", الأطفال الشطر al-'aṭfālu š-šuṭṭaru (literally, "the-children the-skillful").
And then you would continue like that for verbal morphology, syntax, pronunciation, and dialectal issues.