Posted in January, but still interesting. Jonathan Morris compared 3 of the big 4 UK operator's service. Not an exhaustive test, but interesting to see O2 perform so consistently poorly with Three / EE more closely matched.
Coverage is probably still the main deciding factor but if you are in a position to choose EE's 4G premium might not be worth paying.
Now has over one million 4G customers. In 6 months the 4G network carried more data than the entire O2 network between 2000 and 2008.