Current 4G (or 4G LTE) is between five to seven times the performance of the original 3G specification, and as such will offer download rates of perhaps 150Mbps. This equates to roughly 80Mbps download for the average medium strength signal, taking into account concurrent users on the same network and cell. This should equate to you being able to download a 4GB HD film in 6 minutes 40 seconds with a standard 4G mobile network which would have take over 25 minutes on a traditional 3G connection.
A faster breed of 4G is currently being deployed here in the UK. Initially named 4G LTE-Advanced (or LTE-A, 4.5G or 4G+), this improved offering brings theoretical speeds perhaps 1.5Gbps but before you get too excited it will mean a download speed of 300Mbps to us on the street assuming good signal and low contention if it is not prime time for local usage. EE has already deployed LTE-A in London (branding it 4G+) as has Vodafone who have offerings in Brimingham and Manchester also. Availability of LTE-A will increase in the coming years with other providers. 5G is already being developed - we heard that they have run lab testing up to 1GB speeds but of course this will not be representative of the speeds we ca expect on the street. Planned deployments of 5G are for around 2020 and will deliver downloads considerably faster speeds than even 4G LTE-A.
The experience that 4G offers is more than simply download bit rates. It also offers a better response because the latency is lower. Latency is, in essence, how long the device has to wait for a response from the network to which it is connected. A 4G mobile device on a 4G network will wait less time for a response to a request than the same device connected to a 3G mobile network. This improved latency - reduced from the 3G 120 milliseconds to 60 milliseconds on 4G will drastically improve response time for applications such as gaming where many requests are eing sent every second. 120 ms is after all longer than a tenth of a second.
4G is of course completely different in nature to almost every other type of connection. Even Urban Wimax connections rely on satellite location and so are not really portable. 4G however will work no matter where you are as long as there is a 4G carrier signal and available bandwidth. This means that I can buy a 4G router and take it down to a mobile booking office and everyone can use their online booking system as happily as if they were still in their office. It also means that if the local phone network is lost the 4G backup system you thought to install in your internet router in the office will keep working. With new technologies like IP spoofing for the 4G cards - where the email server will continue to receive email even on 4G backup as the 4G SIM impersonates the IP address of the router broadband - allow 4G to be a properly plausible backup and even a primary internet connection for your office in areas without a fibre enabled exchange.
Many of the data only SIMs now available from companies like Three you can have 25GB for £20 pcm which enables most SMEs to run fairly happily and also enables them to more offices without a lot of grief over internet. If you are using serviced offices and they want £80 pcm for phone and internet then get yourself Office 365 and a wireless 4G router and Skype your customers without horrendous expense.