To answer your question, I've been a British citizen since 2006 & had the passport since 2007. That subject is a little too emotive to be discussing on FB, as there is a lot of fear & anger towards both points of view & a lot of scaremongering from both sides of the argument. The biggest gripe you hear about is that Britian doesn't have any control over its borders & can't control immigration, both legal & otherwise. There is also a lot of resistance & anger towards the EU Commission, a non-elected body that proposes & drafts new laws, & implements & enforces those laws that have been passed.
On top of that, there is an opinion that the European Court of Human Rights (not actually a part of the EU) has too much sway over the British Justice Courts; again, a separate argument that gets wrapped up in the whole Brexit (British Exit) debate.
For an example regarding the immigration issue, if UK leaves the EU they will want to strike up a new trade deal so they keep access to the European markets, their biggest export market, like Norway & Switzerland. However those two countries still have to pay into the EU budget, still have to abide by EU regulations & still have to allow freedom of movement for EU citizens, which is where the bulk of British immigration comes from. Britain still has an illegal immigrant problem but they wouldn't gain a whole lot by being out on that front.
Another argument is that the UK pays in something like £350 million a week to the EU budget & this money would be better used paying for British public services & infrastructure. This figure isn't entirely accurate & it doesn't take into account the rebate Margret Thatcher negotiated, nor the many rebates given to British agriculture & other industries such as scienticic research, it being only second to the US in research spending (UK Science would be a big loser with Brexit).
My own opinion is that Britain would be better staying in - I live the no-visa travel back & forth to Spain. There are also inherent advantages for being a part of the EU & if you don't like something about it, you can only change it by being a part of the EU.
Anyway, you asked *:O)
