Well mobile is naturally more like WiFi, distance can be huge if you have direct line of sight to the mast, but add trees and buildings and things tail off quickly. I'm not sure if my speed reduction is capacity or the garden hedge which keeps getting taller, I was actually surprised it worked as well as it does as there are many buildings between me and the mast, even though its only around 330m away from me.
If they add a new one on the end of the street it will only be 95m away with only one building between me and it, just slightly closer than the Vodafone/O2 4G mast.