Well I am in my 20s, married, college degree, and in my last years of pharmacy school now.
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However to me an iPhone was tremendously helpful in college for:
Creating schedules, calendar events, exam days
Flash card study apps
Evernote: viewing power points since my hp at the time did not have a way to view them
Looking up translations/ sparknotes for English
Checking email for school, work, home etc
Mymathlab/ Kahn academy on the fly for calculus
There are many many more but to me an iPhone is like a Swiss Army knife for a college kid. Being able to view/edit/ create documents on the fly is invaluable to those of us with difficult majors.
Now I have learned to appreciate some of its other features like being my Apple TV remote, face timing so my daughter can see her grandma everyday, photo stream, imatch etc.
Now I'm not sure what I'd do without it and I highly doubt any other phone will work well in an already apple setup.