I've given it a few episodes and I think it's pretty terrible. The tone is all over the place, few of the characters are likeable, and I can't help but laugh at the druid magic rubbish. The problem with this vs GoT is that this is set in our world, in a history that actually occurred, and as a result I find the fantasy elements hard to buy into.
One review described it as unintentionally being a bit like a 'carry on' film and I don't think that's inaccurate. Also the Roman leader boasts that there are 20,000 invading Romans yet his encampment appears to house about 200. I just don't think a TV show with a limited budget can do ancient Rome justice. One of my favourite parts of Gladiator was the battle at the start and I was hoping for the tone and scale of that in this show.