This is almost the same price as buying it SIM-free...
LG Optimus 2X - £40.81
18 month contract - £25 p/m (Vodafone)
-100 xnet mins
£25 x 18 months = £450
+ Handset cost + £40.81
Quidco are giving £50, which covers the cost of the handset
So if you can get Quidco then it totals to £440 in total. This is what the phone costs on it own if you buy sim free.
I expect this to get voted cold because it's not the Samsung Galaxy S II.
This is a good deal