In Australia, I was with Telstra, which has by far the best coverage. I was on cotnract. The reason? For $50 a month I basically got (for me) unlimited voice, text and Internet (2-3GB/month). but the 32GB iPhone 4 only cost me $300 with $100 rebate. The handset outright cost $950 IIRC so for $1400 I got the handset and 2 years of service. I don't think I could've gotten two years of service for $450.
In the US I originally went with AT&T as they were the only GSM network that supported the iPhone (T-Mobile could support it on Edge; Verizon and other models came later). Coverage kinda sucks in NYC, really sucks in the Bay Area but in most of the rest of the country is fine.
This was originally month-to-month but ultimately I figured I may as well get the 4S on contract (the discounted price plus the ETF worked out to be no more than the outright price anyway if I cancelled early).
But prepaid? That tends to relegate you to "inferior" networks in the US. T-Mobile and Sprint can give good deals but have really patchy coverage. MetroPCS, as far as I can tell, exists solely for drug dealers and pimps.
One difference is that in most of the rest of the world you don't pay to receive calls. This makes having a phone and not using it much (to make calls) much more viable. Also texting rates in the US are essentially extortionate.
Other countries (Australia and IIRC the UK at least) seem to more heavily discount handsets. It seems like people most often buy the phone that is $0 upfront on whatever plan they want (or they bump their plan up to where it is $0 upfront). The iPhone changed this dynamic somewhat whereas most people seemed to view phones as interchangeable previously.
This article is right about one thing: people do seem to put too much importance on the upfront cost. I see things like the latest gen iPhone is $99 upfront and the previous generation is $49. For $50 you get older hardware that will be obsolete a year earlier... for something that'll probably cost you up to $2000 (or more) over 2 years anyway.