The first is that, if it leaves, it will most likely end up in a situation like Switzerland or Norway (as the EU will still be its main trading partner) where it as to follow EU directives and regulations; allow free movement and contribute to the budget. It will just have no actual say in setting any EU law. So score minus one for democracy.
^^^
It's kind of amazing that the Remain campaign hasn't made more of this, but they're incompetent morons so...
In all fairness, it's hard to find the right "scare campaign" balance for all "pro-EU" parties in Europe (too much and you risk a backlash), it's much easier for anti-EU parties, as they rarely have to deal with the consequences of their actions, and if they lose it doesn't mean a whole lot to them, so they can go down into the rabbit hole.