Horse crap
This is total crap. Nobody cursed with an iPhone on the O2 network in London will accept this bull. I've been on Vodafone for the past few weeks, and the service is incomparable - Vodafone nice & speedy, but you're lucky to get any transfer at all during peak times on O2 - even with a strong signal. This survey must have been done at 3am, if based on real world data at all. I'm highly skeptical.