I live in Finland, so mostly play here, and then occasionally when I go to London (every couple of months or so). Living in a fairly small town I don't have much chance to come across new portals except when traveling, and points are slow to accumulate, so I do play rather passionately when I do travel, much to my nongressing boyfriend's chagrin. I have also made day trips in to Helsinki, for not just unique portals but also the masses of points you can get in just a few hours.
I agree that the game rather can take up what seems like too much of your time (if you let it), but at least it gets you out, rather than staring at your tv with a console game or something. And since I reached level 8 it has been easier to let myself play less, as the levels and leveling up matter less now. I am a little over half way to level 10, have the badges ready for level 11, no hurry with the points, just enjoying the ride at this point.
I am fascinated by the psychological effects of the ingroup-outgroup thing though, and would not have believed how easy it is to program me into feeling that one previously neutral colour is "welcoming and friendly" while another, just as neutral (or previously positive), one is somehow "hostile and aggressive".