I read about half of his works when I was a teenager (strangely, my brother never took to him!), mostly the 'Wild West' stories and several of the Near East ones (I keep coming across place names in the news that I first read in his books), but he also wrote quite an interesting - well, whatever five books in a row are called in English - about the 'Emperor' Maximilian's short reign in Mexico, featuring a forerunner of his 'Old Shatterhand' figure in the German, Wilhelm Sternberg. However, I never got to his later and more 'spiritual' books. The last one I read was, IIRR, 'Old Firehand', and I suddenly felt so disgusted by what I saw as his religious bigotry that I never touched another one. I suppose you know he never visited any of the places he wrote so vividly about, and also suffered from a massive inferiority complex which led him, as a young man, to stealing from fellow students. He also got jailed for fraud but seems to have got back on track by putting his delusions of grandeur into his books. Many of them are great reads but might not feel very authentic to an American raised on J. F. Cooper!