The example given in that article is very much the exception rather than the rule, and most contracts are essentially a loan, which almost always includes an element of interest that needs to be paid. I prefer to buy a phone outright, and take advantage of a sim only deal. That way you can get the best of both worlds, an unlocked handset, and a tariff that's meets your needs.
But the old adage about shopping around still holds true, so it's best to look at all options. If you're patient enough, it often pays to wait before buying the latest flagship model, because prices can fall markedly following their initial launch. But if you can find a pay monthly contract that works out cheaper, and I've seen a few, then go for it.
As far as I am concerned, it is not always the cost involved in using a mobile phone whether at giffgaff or anywhere else, for me the real bind is the thought of being tied in for two years or so. I prerfer the freedoms and the options we have here with no tie ins.
That for me, is the beauty of Giffgaff, monthly goodybags, which can be changed whenever you wish and NO TIE IN.
Regarding the phone, rather than take what is on offer with a contract, i have chosen to pick the phone I want and not what a contract would give me.