I have to away from my S4 for one week and has been using a feature phone 4 days.Things I really missed:
My most is GPS/Maps. Even not for travelling, a daily route I frequently have google tell me exact times and routes for transit than remember it or figure it out. I turn on Gps often and battery drains fast so I also missed my beast mpj extended battery. I also tend to not know where streets are in relation to each other so just Map everything. Other than those, killing time with ebooks, and occasionally texting or calling people.
Wondering ur #1 use on phone