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You don't want your fathers first experience of owning an iPhone to be a bad one, and the much slower performance of the 3GS on iOS 6 along with the less than stellar UI animations means that your father may end up more frustrated with his first iPhone rather than loving it and becoming a long standing iPhone user and customer.

Just my thoughts.

with my parents they both have ipads and good cameras, the 3gs's are way better than their old nokias, they only wanted them if they were cheap, they only use them for phone/txt/music, i offered my mum my old 4 and she said there was no point as the 3gs does all she wants :)
 
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