I'm loving it. First smart phone thingy I've had after running crappy phones and I'm completely amazed by what it can do. Its pretty easy to use. Took me about a day to get everything I wanted on there and to get use to it.
Its good enough to have upset a few of my mates with iphones..
If you do go for giffgaff, rather than ordering a sim from the site, if you PM me your name and address and let me order it then we will both get £5 free credit
They also work on phones locked to o2 so save yourself some pounds by getting a locked one..