I just gave up a game after my third and fourth expansion sites were gobbled up by stations. One station alone, blocked me from two of the five petroleum resources in my territory, along with copper and fruit resources.
Nearby was one of three "titanium" sites in my territory, on a peninsula, which would have been absorbed by natural city growth. The other two titanium sites in my territory bordered on other civs' territories and occupying either would have led to an early war.
I waited for the dust to settle around and the reviews to come in on BE, so am still learning the quirks of the game. I have not found any early game military advantages such as "Iron Working" in Civ 5, so consider it counter productive to expend precious resources on building up a large army right away.
It does however appear to be a deliberate strategy of the AI to consume the best sites - but it does nothing to enhance play, when strategic resources are swept off the table. From what I am able to observe so far - occupying prime expansion sites seems to be the principal effect of stations.
I am still not satisfied that I gain greater benefit from establishing my first trade route with a station, than I do from creating my own internal trade route. I think my next move is to start taking them out.