Finished watching "Penny Dreadful". 3 seasons, 27 episodes. After the first 4 or 5 episodes of season 1 thought it was Plenty Dreadful, but I continued to watch and it did get better. Not great, just better. Each season is a different story line with maybe an additional character or two. The bad guys are plenty bad, the good guys are bad, but good if you know what I mean. The finale was controversial and I can see why, but it we done is a way that makes it less annoying than GoT was. I hated the ending of GoT, but I understood why they ended it that way. At least, PD ended for the most part although they left a few loose ends. There will be no season 4, that was announced some time ago. I suppose they could resurrect it if they wanted to but it would have to be a lot different.
I will give it a 6 or 7 out of 10 and if you like Gothic horror you might like it a bit more. There is some excellent acting in this show. The guy who plays Frankenstein's monster does a great job portraying the sympathetic beast Mary Shelly wrote about. Eva Green does a good job as the lead character conflicted by good and evil. There are other characters lesser who are very good as well.
I like how they took all the characters from all the classic horrors novels and woven them into this series. It starts on a good premise.