GiffGaff anyone?

I just wondered if anyone had looked at giffgaff.com, or whether it's just me that's taken an interest in this?
GiffGaff is a mobile network, which is reasonably cost effective (run on community power, no call centers etc. xD). And it piggy-backs o2 (to put it simply).

Any of you guys used GiffGaff?

Couple of useful links:
http://giffgaff.com/ - home
http://giffgaff.com/index/offer - prices etc.
http://giffgaff.com/index/us - about GiffGaff

Recent thread about giffgaff: http://www.habboxforum.com/showthread.php?t=681221

I have a giffgaff sim lying around somewhere, not tried it out yet but it sounds decent.

Yeah i've tried it out, you get like a fiver for every person you get to signup under you + you get free internet usage till feb and their packages are quite cheap and their signal is pretty decent as it works off o2. so yeah overall its good.