This deal will probably go cold but for me it is a pretty sweet deal if you include the extras, are with BT and want a 64GB SE. In additional to the half price this includes a £100 Amazon or iTunes Voucher and there is £60 cash back on topcashback.
My wife wanted and SE for a while and only worth having the 64GB version. There is a similar deal with less data too but this again is less appealing for most whereas 3GB is decent. Don't forget I think you also get BT Sport 1 and BT WiFi hotspot included for the whole 24months.
To make matters less confusing it works out at about £7.20 a month for 1000 minutes, unlimited texts and 3GB data if you include the extras and take off the handset cost at £399.