I use it as my main network/contact.
I use hullomail with my iPhone 3gs, gmail on exchange synching mail, calendar and contacts.
Service works perfectly - support is superior in terms of speed and quality of response.
It's in my nature to use more than one network, but my giffgaff SIM has found its home in one of my 3 main phones. My O2 number is still the one most of my international contacts have, while giffgaff suits me fine for domestic use and for texts to certain countries.
3Uk is my main network with my number on it. Still on the Flat12 PAYG tarrif which appears to have avoided the recent price hikes on PAYG.
Its a close run thing at the moment to stick with 3 with there topup bonus's of 150Mb data, 600 texts and skype access.
Just waiting to see what GiffGaff do with data charging and packages such as bundled landline calls like TMobile do.
Just running the rule over the coverage in my normal places etc and checking all my data applications work and are not blocked etc.
I really like the 3 network, and quite tempted by TMobiles latest offerings, but GiffGaffs keen prices and community spirit is also tempting. Voda Orange and O2, for me, are way behind.
I still have a little while to run on my Three contract, they give me free internet but only 100 mins/texts. Being a tightwad, I have moved the whole family over to giffgaff, which helps budgeting no end. Data charges could be the only sticking point, it would be nice if we had some advance notice of what the costs are likely to be after May.
Giffgaff has taken over as my main network from Vodafone and when I run out of credit on Vodafone I will seriouslty consider whether its woth topping up again given the superior package on offer from Giffgaff