Wonderfully atmospheric
I just finished this and really enjoyed it. The atmosphere of mystery and dread was so thick I could taste it (literally, I have mild synaesthesia.) The best episode in this regard might have been Creed, OK where Ben meets the mask maker. That entire sequence in his "workshop" was terrifying and I liked how it seemed ambiguous as to whether it actually happened at first.
It sucks that the show was cancelled, and I would kill for 4 more seasons in this fascinating world, but I actually thought the ending was pretty satisfying and final feeling apart from Sofie.
The main thing I didn't like about the show was the strange focus on the Dreifuss family. It simply was not nearly as interesting as everything else, and at times felt dropped in from another, inferior and more soapy series.
But in terms of an overall cohesive product, Carnivale is by far the best out of any "mystery" TV drama, even something like Twin Peaks which loses its way badly. I felt like the makers of Carnivale had a firm grasp on their story and mythology and the result was not only riveting but intellectually and emotionally satisfying, cliffhanger and all. Bravo.