It all depends the person. If you have prior experience with other languages that are highly inflected, e.g. Latin or German, Ancient Greek will come more easily to you. I find that people struggle most with the high degree of irregularity. There is a great deal of memorization involved in learning the principal parts of verbs. Also, Ancient Greek has a number of dialects that complicate things further. Homeric Greek, for instance, is really a thing unto itself. If you are determined and commit the necessary time, I'm sure you'll do fine though.