I have read most of what has been published for the manga (a volume or so behind I would guess). I had not remembered at all that the opening chapter begins with the funeral of Ars's father (I looked it up to check). So, I was quite confused for a minute there.
Overall, this first episode looked really nice. I can't really complain about the animation too much. Even the fight scene with Rietz looked pretty good. The one complaint I will lodge is that the depiction of Ars's ability is much harder to make sense of in anime than in the manga. Compare what was shown in the show with this:
Based on next episode's preview, one of the more fun members of the retinue is showing up next. My favorite member doesn't come until much later, but she is in the OP, so I am looking forward to that.