I have to say I had an advantage in that I speak both English and French fluently, therefore I did not need subtitles, but the story itself is interesting enough that I don't believe subtitles would diminish the experience.
It was refreshing to watch an apocalyptic event that had nothing to do with Americans, and although the action is fairly minimal with more attention being paid to human interaction, it was fairly enjoyable with mostly good acting throughout.
I also enjoyed the fact that someone in the show actually pointed out what I always think during this type of story; Why would aliens attack Earth when the resources available here are readily available elsewhere in the galaxy?
Although the question is not exactly answered at the conclusion of the first season, we come to have a general idea as to what is going on, if not the details.
I would recommend this so long as they produce a second season.