I was looking through some esoteric books, and I found a book by Rudolf Steiner. So far, a lot of the other authors that I looked into just didn't feel trustworthy, but Rudolf Steiner and his language in his writing feels "right" somehow. I looked him up and found that he was a philosopher. Has anyone ever read any of his books?

Steiner is outstanding person. He played a huge role in development of esoteric science. He was a founder of anthroposophy. This spiritual science aims to make scientific basis for studying supernatural stuff, build the bridge between religions and common science. Anthroposophy made new trends: in social science - movement for social trinity; in pedagogics – Waldorf school; in natural science – geteanistic science; in medicine and pharmacy - anthroposophical medicine; in agriculture - Biodynamic agriculture; in art - eurythmy, sometimes referred to as "visible speech and song". He found out the revolutionary relationship among world religions (Christianity, Buddhism, Islam, Hellenism, Judaism) in past and nowadays.
Complete works (books, lectures etc) of Steiner includes 354 books.
I have just started to read and learn his books and they are so unusual and amazing. I should say it is not an entertaining reading at all, sometimes it is really hard to read if you are not aware of Bible in a very good way.
I finished reading “Apocalypse”, “Christianity as a Mystical fact”
Now I’ve decided to read something which has no connection with Christianity and the book “Fundamentals of Therapy: an Extension of the Art of Healing through Spiritual Knowledge” is on my bed table. It is so interesting and I recommend reading it.

Oh, I like Stainer a lot. How he wrote about Christianity in a manner everybody could understand. He was often described as a original and neo romantic thinker, who has a strong, practical impact today in many spheres, especially in education, medicine, agriculture and the pictorial arts. I can't say it is a great way of education, especially in religion, but I found a lot of interesting things in his books.

Rudolf Steiner wrote and spoke in German with a Viennese accent .which was considered very nice and special. Just a small part of his work has been translated into English. English editions of his books can be bought from the SteinerBooks and all the usual booksellers. German copies are available through European book channels, or directly from the issuer.

Steiner left all his books and literary properties to his wife, who opened a foundation to manage them. The Rudolf Steiner Nachlassverwaltung has keps all 300 volumes of his work over the last 80 years and maintains the archive of Steiner's old documents and manuscripts in Dornach, Switzerland.
There is a Online eLibrary for English readers looking for online resources. This is considered to be only one best and most comprehensive online collection of his work in English.

I can also recommend the following very very interesting and capturing books, for thos interested in Rudolf's books:

777 and Other Qabalistic Writings of Aleister Crowley
Aleister Crowley, Israel Regardie

The Adornment of the Spiritual Marriage
With The Book of Truth & The Sparkling Stone
Jan van Ruysbroeck

The Alchemical Mandala
A Survey of the Mandala in the Western Esoteric Traditions
Adam McLean

The Alchemist's Handbook
Frater Albertus

Alchemy of the Soul
The Eros & Psyche Myth as a Guide to Transformation
Martin Lowenthal

Alexandria 1,2,4,5
Cosmology, Philosophy, Myth, and Culture
David Fiedeler

Ancient Egyptian Divination and Magic
Eleanor L Harris

The Angel and the Sorcerer
The Remarkable Story of the Occult Origins of Mormonism and the Rise of Mormons in American Politics
Peter Levenda

Apocalypse of Baruch and the Assumption of Moses
Robert Henry Charles, R.A. Gilbert

The Arcana of Freemasonry
A History of Masonic Signs and Symbols
Albert Churchward, R.A. Gilbert

Art and Practice of Caballa Magic
Ophiel

The Art and Practice of Geomancy
Divination, Magic, and Earth Wisdom of the Renaissance
John Michael Greer, Lon Milo DuQuette

Aspects of Occultism
Dion Fortune, Gareth Knight

Awakening Osiris
The Egyptian Book of the Dead
Normandi Ellis

The Best of the Equinox, Sex Magick
Volume III
Aleister Crowley, Lon Milo DuQuette

The Blazing Star and the Jewish Kabbalah
William Greene, R.A. Gilbert

The Book of Black Magic
A.E. Waite

The Book of Jubilees or The Little Genesis
Robert Henry Charles

Book of Lies
The Disinformation Guide to Magick and the Occult
Richard Metzger, Grant Morrison