I personally have not mastered Fusha. I am just scratching the surface and have been learning for a few months through some university courses. I am personally only interested in learning it so that I can read the Qur'an, beyond that I have no motivation, but unfortunately there are like four levels of Arabic you have to through at my school before such classes even become an option. Learning the alphabet was a bit tricky at first, my only struggles have been with memorizing plurals, مصدر forms and other things along those lines. In comparison with the other languages that I have experience with, some of these alterations are insane. I need to step it up, honestly. If you're interested in reading the Qur'an above all like I am, check out this book:
It only assumes that you have knowledge of the alphabet and starts a lot of the shorter surahs like al-Fatiha, an-Nas, al-Ikhlas, al-Falaq, etc. I'm not that far in but I'm enjoying it.