I've just seen this movie tonight on Melbourne's SBS TV channel and had to see what others had thought of it (a pity the professional reviews are all in languages other than English). No matter. While it took a while for the plot to get going, I was engrossed from the beginning. It's great to see non-Hollywood actors (who can also act) in a good movie. For me, seeing unfamiliar faces in a thriller/drama adds to its impact, which doesn't often happen when I see so-called Hollywood "stars" who just can't forget their "star" quality... (eg Cage, Cruise).
Some of the events in The Third Wave relied a little too much on coincidence to be believable, especially toward the end. And the Munich riots in the last section were rather "over the top" (I thought I was watching 28 Days Later at one point) - it was reassuring to read others' comments that such wild behaviour wasn't typical of protests in Munich.
Nevertheless I was totally involved - I initially didn't have a clue who was to be trusted (thanks to a good script) - and the film's overall quality warranted my forgiving its unlikely coincidences.