Its an Indo-European language, so if your native language is Indo-European, then you will encounter many familiar structures and words. (There are quite a few Persian loan words in English, btw.)
The script will likely present the greatest challenge. It is Arabic but nevertheless it is an alphabet. Beyond the letter forms, you will need to adjust to the idea of positional capitalization and joins.
Farsi/Persian also has a fairly complete coverage of various sounds, some of which may present a problem to the non-native speaker.
Finally, Iranians do have a fairly distinct partition between formal (written/official) language and the everyday conversational usage. The conversational style is much more fluid.
Although I don't know Farsi one of the instructors at my college said it was one of the easiest languages to learn. She said many of her students were writing Farsi poetry by the end of the semester.
