I've used Feel At Home quite extensively (more when it was still called 3 At Home) and it's fantastic. The two countries I visit most often, USA and Spain, have recently been added to the list. I'll be able to get rid of my international SIMs and cut out the logistics of having to swap then while travelling. Free data roaming is just about the best thing a network can offer customers who travel.
Glad to hear it works well, as I am currently with TMobile and was horrified by the prices for going to the USA. I may even switch to 3 for my "daily driver" phone.