So we actually got a 8 episode second half of the season, which concluded tonight, with the last few episodes building together nicely to come up with a "strong" finale/cliffhanger, and it looks like there will be a third (and my guess) final season. The pieces are in place for a final season that resolve the alien invasion.
Overall, the show started moving a little closer to X-files instead of dumb sci-fi comedy, although there is still a lot of that. The addition of Linda Hamilton and Terry O'Quinn helped anchor this in sci-fi familiarity, but it is the stories of several of the secondary characters (Ben, Dep Liv) that brought a more serious undercurrent to the show, and makes me wish we had had a lot more of that all along.