I’ve friends that have used giffgaff for a couple of years with no complaint, and I’ve just switched to them after my contract with Vodafone ended. Porting my number went flawlessly, although there was a worrying lack of feedback during the process. It’s only been a week, but I’m impressed so far, and get a warm, fuzzy feeling from being with hippies that have knitted their own virtual network from organic yoghurt and flax seeds. Interested to see how coverage compares when out in the wilds. Remember that if you don’t like them, you’re not locked in and can leave whenever you like.
Can’t help wrt unlocking, bought my phone SIM free.