On the contrary, the acting is fluid and it meshes well with the show's tonal shifts. As for the grit, that accentuates the battle scenes and the battles generally have a lot of strategy to it. It doesn't come off as clean. It's very real and you can admire the tactics that are used. The battles are not just bloody, they're intellectual.
Do you even watch the show? 
I swear we must be seeing two different shows.
Where you see Fluid, I see amateurish and wooden acting with painfully forced facial expression and tone of voice. Nothing natural about it other then the painfully constipated look Fimmel does whenever something "dramatic" happens.
And again Grits are merely ground corn, saying that expression doesn't make it more then it is 
And Strategy sure, as in rush in there and kill folks, sometimes with the assistance of Archers! You know just to switch it up, GOT at least has half decent source material to draw back on, The books detail some fairly decent battlefield stratagems employed during the larger battles.
And their not overly bloody, not necessarily a failing given that gore for the sake of gore does not a war make, But to me? It isn't overly intellectual either 