We were in the pub! It was interesting to hear the differing times people's phones went off. One was as late as about 15.07.
I am 3G and never got a thing. DS13 had his go off and was quite excited about it (he was told beforehand).
Then it triggered a pub-wide discussion about what it might be used for - nukes or tsumanis.
It was kind of fun. (Boring life alert!)