I honestly thought it was a decent watch. I just enjoy watching Michael C. Hall do his thing.
The writing for the episode was admittedly not great - Harrison showing up the same day that Dexter finally kills again is a bit contrived. Although maybe they are trying to imply that it's what finally pushed him over the edge? Either way, I can forgive this in order to set the season up. Also the symbolism of the white deer was fairly heavy-handed.