If you're in the market for a new mobile contract then this looks like a great deal.
500 cross-network mins + 5000 texts + All-you-can-eat Data • 24 months
Sony Xperia M
If you don't like this phone, sell it as 'Brand new in box' and buy a phone you do like.
Yes, you'll be tied to a 24 month mobile contract @ £35 a month, but if that's what you'd normally do anyway, then the free PS4 is a great deal.
There are a few deals available, says 2-3 weeks for delivery of the ps4.
All deals - http://www.buymobiles.net/freegifts/free-sony-ps4
Cheapest on 3 - LG Optimus L5 II - £33 p/m (£768 total £349 for console contract worth £309.60 so paying £109 for the phone)
Cheapest overall is £29 p/m on various phones, but low data on those contracts (Total £696)