Would it be smart to exchange xperia z 5 months old.with an iphone 4s 32 gb?

Iphone 4s is 1 month old and of white colour.
xperia z have billing of april and is of black colour

Its upto you… Xperia is also good

Hell no!
The 4s is inferior in every way.
The xperia is a much, much, much better phone.
You will regret it if you do.