Great show! Characters are credible, good acting, great costumes and convincing location. I was pleasantly surprised to hear the Romans speaking in Latin and the Germanic tribes in German. Of course Germanic languages in Roman times sounded nothing like modern day German but as far as I know there are no records of what it sounded like back then... The producers went for the best option in my opinion. The build up of the events that led to the big battle of Teutoburg Forest got me hooked from the start. A lot of historical productions are slow, this one isn't.
Unfortunately, as a history nut, no single television production is (entirely) historically accurate. As mentioned before by someone else: the Roman gladius was designed to stab and it would not have been possible to chop someone's head off with, just to name something...The battle itself was over fast, too fast, the show made it seem as it was a walk in the park while in reality it was a 3 day battle. In my opinion they could have done more with it.
I absolutely recommend this show. Was hooked from the beginning: started watching around 3 in the afternoon and finished at 10 in the evening the same day.