Comes down to life/workstyle, IMHO. When I lived in NYC during the late '90s and early 2000's, I lived and died by a Palm Pilot (granted, not a smart phone and the onboard data was only as current as your last hardwired sync). But scheduling and contacts, apps for restaurants, shopping, entertainment venues, subway and train info, city walking maps... All had a practical function when I had 3-4 meetings per day — not per week; when dining out or ordering in was the rule and cooking the rare exception; when I moved around the city via mass transit (or more often on foot) instead of a car.
Having my calendar and contacts always up to date is the only feature I see as truly practical — relative to my current day-to-day. My policy is to do or buy stuff because I should
, not because I can.
* So, since a smart phone is not presently a how did I ever live without it
thing, I'd rather start on a lower shelf, and move up only if or when there's added value to be had. But I may wait for the 4s prices to fall because the extra speed is still nice to have.
*I break this rule only for scotch. I'll drop $80 on a bottle of Johnnie Walker Black because the $45 Red just ain't as satisfying!