Hidden Features of the PS4
Using a PS Vita as an extra controller
Pretty handy i must say.
The only problems (thus making it less than ideal as stated in the article) I can see are the lack of dedicated L2/R2 triggers and any potential lag because this is actually a whole console rather than a controller. All in all, a casual gamer should hardly be concerned.
40GBP is pretty steep for the Dualshock. Over here they're selling at $60 + tax if that's any indication.
Also, the power draw from keeping USB powered up in standby is overrated.