I've just finished watching all of it. That was a strange little experience. I felt that it didn't start out that great, but improved with each episode. Really for the entire first half of the season I just felt confused and a little frustrated, but it all started to come together towards the end. The last four episodes definitely held my attention better than the earlier ones did. The ending left enough open for a second season but also provided some closure on current plots.
If I were judging solely on the quality of individual episodes, or how the series started out, I wouldn't rate Hemlock Grove very highly. But taking it as a whole, I thought it was worth my time. Unfortunately most people won't be willing to stick around for several episodes to see if it improves.
Also, if anyone is expecting any sort of realism, not just in the fantasy sense but also in terms of dialogue, characters, settings, etc. then this is not the show for you! People don't really talk this way, teenagers don't act like this, towns don't operate this way, families don't interact like this and Fish and Game representatives don't act this way. Nothing about this show is realistic, but that doesn't mean it can't still be entertaining.