One potential problem with traveling during the off-season is that some attractions are closed or have restricted hours. This I believe is only a minor setback, however, and can be easily overcome with careful planning. Frequent trains and buses. You won't have to pack heavy winter clothing. Attractions are crowded.
Hostels are crowded.
Crowded trains and buses, and costs more than in the off-season. You'll meet lots of tourists. Hostels are less crowded and sometimes have a reduced price. You'll meet lots of world-wide and domestic travelers. You shouldn't have to do laundry as often, if you aren't stinking up your clothes with sweat.