I have to agree with you, I live right in the city centre of Aberdeen and get ZERO O2 signal, moved to 3 about 18 months ago and get full bars at home now.
Download speeds in excess of 7mbps and not uncommon! and I travel all over over Aberdeenshire for my job and even find myself getting HSPA+ signal in the middle of nowhere when my work phone cant even get 2G (O2)
The one plan is amazing value for money, the might aswell just call it unlimited everything as I can't really see anyone using more than 5000 texts of 2000 minutes (+5000 3 to 3 minutes). I pay £35/month and £88 upront for my 32GB iPhone 4S and love it!
Cant wait for LTE to start rolling out, looks like 3 may be a late starter, but I'm confident that they'll do it right!
Getting about 15mb down and 900k up on Sky DSL, not bad when it's free! Can't wait for FTTC (30-6-12)
Disclaimer: I work for sky, but have no involvement AT ALL with broadband, so dont ask!