My BT broadband is lucky to see 3MB down or up at any time of day. Mine and my wifes Three 3G phones get 8-10MB down and can tether to any other device in the house.
My brother with his iPhone 5 on superfast 3G with Three saw 19MB down!
My thoughts on 4G at the minute is that phones will be searching for 4G signal alot and therefore drain battery quicker until there is a more consistent and established 4G newwork / antena hardware and infrastructure. (just my theory lol)