Really dIsappointed to be honest. It doesn't seem to have a main feature, the 4 had retina display then the 4S had Siri. This is kind of a catch up rather than leading the field. It does look good though much better than the competition.
I went on sim only a few months ago so probably stick with my 3 year old 3GS for a while, even though the battery lasts half a day when it's used!