Brexit is a restructure of British relation to the EU. It cannot do that much to effect the economy of Britain. As well, Brexit might have been taken full effect yet, meaning that the effectiveness of changing the British economy is severely reduced. It's kind of a waiting game on what happens next for both the UK and its economy.
The initial market reactions to Brexit were all reactionary based on the unknown nature of how Brexit would be carried out. While it's still too soon to know the actual process of the separation, things seems to be settling into a more normal state pending the government's action. Long run, the effects on the UK economy could still be massive, or they could be slight. Only time will tell.
Many people within the UK and in other countries were strongly opposed to Brexit for their own self-serving reasons. They attempted to portray the move away from the EU as something that would be economically disastrous to the UK. In reality, Brexit has been and will continue to be positive for the UK in many ways.
As an American, it was fascinating to watch the entire Brexit debacle taking place. The fear that the "stay" side was trying to pump into the people was simply amazing. Getting out from the EU's 'oversight' and decoupling from the Euro was the best thing that Britain could have done, and now they have more control over their destiny.
The short-term impact of Britain's exit from the E.U. were widely predicted (although some forecasts were more dramatic than others), but a great deal of economists, political scientists, and other academics noted that these would most likely be short-lived effects. Exaggerations of Brexit's impact, made worse by speculation and lapses in confidence, were more political than economic.