Just watched this off Netflix.  I'm of mixed emotions about this,  The voice casting, performances, and animation is top notch, but it is marred by the same old "heroes unite under threat of aliens".  That is really getting annoying.  I realized how much that chestnut is abused with the JL pilot.  And they used it with Ultimate Avengers too.  Overall though, I highly recommend watching this. In particular, I loved Neil Patrick Harris as the Flash and David Boreanaz as the Green Lantern.