The Sidur of Saadia Gaon tells us some things that we might not know. I thought for a long time the basic blessing in the morning before the Shema was  elongated. But I was not sure about what part. The reason is that it seemed to me there was something in it that was essential besides the first sentence and last. That is I did not think it was like a simple Bore nefashot with a חתימה
[ending]. Someone showed me that in the sidur of Saadia Gaon, the first blessing is, in fact, just the first sentence, then the one sentence after that, and then the last חתימה [ending].

At any rate, my opinion is that the writings of Saadia Gaon are important because Yidishkeit has gone way off the path already for too long.