Just finished to watch it. Not a total masterpiece for me, at places it's a bit slow and convoluted, but Tom Hardy mmm-mhing his way through London and delivering sheer badassery back and forth and Jonathan Pryce cursing like a sailor are total highlights of the show, followed closely by the always horny chemist.
The only main character that was a bit of a letdown was the sister for me, she didn't do really anything except for being sulky and clearly aroused around Delaney, and then she just jumped into the river at the end.
Also I'm still not sure that the reveal that Doug Stamper was in league with the EIC makes much sense, but all in all the final episodes were really great and redeemed the less stellar episodes that came before. It's nothing alike Penny Dreadful but it's a distant relative in spirit and tone in a sense.