@Arthur I wrote that post - thanks for the link! I should point out that GiffGaff have announced that they are introducing recurringgoodybags on 20 June 2012 - so this week my post about the "gotcha" becomes a non-issue.
@fiza As I'm a new user at EduGeek, I can't include a URL for the source of that info but I've updated the post @Arthur linked to. As for coverage, GiffGaff is an O2 MVNO (in fact, they are owned by O2). From having used them for a few months now, the main difference is community support (forums, with online "ask an agent" for account stuff), some functionality (no Visual Voicemail, for example, AFAIK) but basically you save some money instead - if you're happy with that tradeoff (and you get decent O2 coverage in places where you travel), then you should be fine...
Mark
