I just watched Season 1 for the first time. This thread convinced me a few months ago that I needed to watch it after I finished Game of Thrones, and I finally got around to it.
I really wasn't feeling it through the first 2/3rds of episode 1 (until Caesar sends Lucius and Titus to recover the Eagle and we get some adventure, action and the start of the bromance), but I was hooked after that point. I also had a little difficulty not seeing McKidd as the doctor that he played in Grey's Anatomy, since that was the only thing that I knew him from, but that gradually wore off.
I agree that Mance Rayder was perfect as Caesar. He was both likable and intimidating, so that you would sympathize with him being murdered (if that's a spoiler for you, learn your history), but you could understand why others would do it.
I really can't seem to get away from Tobias Menzies (not that I want to). It seems like he's in everything that I've been binge watching lately... Rome, Game of Thrones and Outlander. Perhaps he's the secret ingredient for a hit show. I'm halfway surprised that he hasn't made an appearance in Black Sails yet.
I do have to say, though, that the opening credit sequence of every episode really didn't do anything to me. It seemed far too artsy and weak for the tone of the series. An intro more like Game of Thrones would've suited it better, IMO.
Loved the show, absolutely loved it. I remember there being some talk about a possible movie a few years back but I guess that's not going to happen.
Apparently, a movie was still on the plate as recently as 2014, and if six years from the earliest rumors wasn't enough to kill the project for good, two more since probably isn't, either. It makes you wonder, though, if how poorly the Ben-Hur remake is doing could scare them.