I want to watch the anime, but first I need to read the light novel. Thus, I wanted to know how much the anime adapted the light novel and whether or not the anime skipped any content?
They skipped a particular loop in the anime when Subaru went to the mansion to warn about the incoming witch cultist attack.
In this loop,
Subaru tries to convince the mansion residence to evacuate. When he tried to convince Beatrice to move out, he failed and learned a slight clue about who Beatrice really is. Then he was killed by the witch cultist later on and restart again.
From what I remember the anime went to part way through volume 10, maybe even less. In terms of the adaption, from Volume 1 (only one I've read so far) it adapted about 80% of the content.
Think he's died a few more times in the LN.