I have to say that immigration has never really been something that particularly bothers me.
It's definitely a positive to have ready access to genuinely highly skilled people going into genuinely highly skilled jobs. I hope we retain that in the future.
On lower skilled jobs, I would quite like to understand the fiscal impact a bit better. I know that, on a very simplistic measure, EU migrants as a whole bring in more in tax then they take out in welfare benefits. It would be good to really understand how the figures work when you look at the amount 'taken out' in services and (in particular) the amount required to be spent on capital infrastructure like primary schools, housing and GP surgeries, together with the wider effects on the economy of house price pressure. One has to earn a surprising amount to be a true net contributor to the economy. Whilst many EU migrants will, I do slightly struggle to understand how, in London, Pret à Mangers on every corner full of degree-educated EU migrants on tax credits can be doing any part of the EU economy much good.
I'm willing to be convinced either way if there is decent data.