We moved from a big UK city to Germany. both dh & I wanted to go. I've never regretted a minute. I was fed up with UK & wanted to go for ages. Luckily dh was as keen as me.
Issues I've found ; language. It is hard, even if you alrerady know Spanish/Italian/whatever. You are always marked out as an outsider. Plus, no matter how good your language, there can often be times where you can't say what you need to say and that can be very frustrating & humiliating. If you don't know the language, it can make things very very difficult on a daily basis. Plus it would make finding work very difficult if not impossible.
Family. I get on really well with my family, but we're not very close as such so it's not been too bad, although it has worked out expensive ('phone calls) for us and for them (as we have young children it's not so easy for us to travel, so family tend to come to us).
While neither dh or I miss them, dd really does, and asks all the time to go & see grandad, which makes me feel bad. It's very upsetting for her when a visit comes to an end. Friends in a similar position who are closer to family find it very hard themselves.
We rarely get to go out because baby sitting is so expensive & obviously have no family about, and not really any people to make reciprocal arrangements with.
Loads of other negatives,
But, like I said I love being where I am. Every day I think how lucky I am. I'm glad I left the Uk and don't want to return. A couple of times I have felt 'homesick', but i usually get over that about an hour after landing, then can't wait to get back home to Germany.
Good luck with whatever you decide to do. Oh, and if I can be of any further help..