Glad to see Erin mentioned. Its my favorite anime after K-on!! and its a shame almost no one knows of it or talks about it. I don't really agree with you saying that is has filler episodes outside of the two recaps and the one ep that focuses on the two idiots whose names I can't remember right now. The show is paced very slowly, but everything feels important and adds depth to the characters. Erin herself is such a great character and I love the way she develops throughout the series. I wish vol 3 & 4 of the LN would get adapted, but the author did originally plan to end it in vol 2, it does have a conclusive and satisfying ending.
Anyways, you can clearly see that I highly rec Erin