Yes - you are quite right to say that Sri Aurobindo's philosophy is quite complex - also, his writings are quite voluminous. They are intended only for the serious seeker. The system is complex on the face of it, but once grasped, or seen, has a beautiful simplicity about it too. It does not contradict any form of true spiritual endeavour or yoga.
As well as works by Sri Aurobindo, there are also a number of books by Sweet Mother, which consist mainly of records of talks, inteviews etc, as well as some of her own writings.
There are several books about Sri Aurobindo that seek to introduce his work. About the best I've read is 'Sri Aurobindo and The Mother' by Kireet Joshi, and more controversially, 'Sir Aurobindo - the Adeventure of Consciousness' by Satprem.
However, the only way to get a true impression of the value of the man or his works is to read the originals.
We English speaking people are fortunate in that English was Sri Aurobindo's first language. (later he became an authority on Indian languages) He was born to heavily Anglicized Brahmin parents at the hight of the British Raj,(august 15th 1872) and sent at an early age to England to recieve a western education. He proved to be an outsatnding scholar at St.Paul's School, and later at Cambridge.
Returning to India, he became a professor of languages at Baroda University, and became a prominent and leading figure in the movemant for Indian Independence. He was briefly imprisoned and tried for suspected involvement in the Alipore bomb plot, but was fully cleared of all charges against him.
It was at this time that Sri Aurobindo was introduced to Yoga, something for which he turned out to have an absolutely extraordinary capacity. He tells how in only three days practice, he has attained to full mental silence, and he continued to have many revelatory spiritual expeiences.
Partly to escape British persecution, and also on the insistence of an 'inner voice', he then moved to the then French controlled Pondicherry, where he remaianed for thr rest of his life. He retired from involvement in politics, and devoted himself to working out the details of his 'Integral Yoga', and doing intense Sadhana. From this time, date many interesting works, which were originally published in 'Arya' a magazine started for this purpose.
With the arrival of Mira Alfasa (known to devotees as 'Sweet Mother' or just 'Mother')at Pondicherry in the late 20's, a proper organized ashram was instituted. Shortly after, Sri Aurobundo retired to his suite of rooms to pursue his sadhana, leaving Mother to organize the Ashram, which she continued to do until her death at age 95.
Only twice yearly, Sri Aurobindo would appear publicly at the Ashram to give Darshan.
Sri Aurobindo left the body in 1950.
As said earlier, Sri Aurobindo's philosophy is complex, and it wouldn't be possible to give any kind of adequate overview of it here. A few remarks though might show something of the general direction of the work.
Sri Aurobindo really sought to make a new 'synthesis' of knowledge. He draws from manny of the traditonal paths of yoga, on which he was an expert, but brings them together in a new way, and also incorporated as a fundamental principle the idea of terrestrial evolution. He sees spiritual evolution and the evolution of the universe as being linked. He differs from Darwinists though and insists upon a Divine origin for all existences - evolution is seen as a progressive manifestation beginning with, and culminating in, God.
Whilst most paths of Yoga speak of the goal as liberation, Sri Aurobindo does not disagree, but says that there is also a possible further step of Yoga - transformation of earthly life. Human life into Divine Life.
If someone asked which of his major works is most essential, I'd have to say 'The Life Divine'. But even though this is some 3,000 pages long, there are still many aspects of his work which aren't covered.
A great deal of insight into Sri Aurobindo's person can be had in Dilip Kumar Roy's 'Pilgrims of the Stars', where he describes his meetings with the great Seer who was to become his guru.
Sri Aurobindo