It is very difficult to explain what is unique about the Orthodox Church without discussing the 1700 years of history between present day and the official recognition of Christianity by Constantine in 312 A.D.. In brief though, what has made the Orthodox Church different is that the laity are considered equal in important to the priests, bishops and patriarchs when in comes to matters of religious doctrine and theology. In other words, throughout history the ordinary members of the church have had just as much say when it comes to doctrine as the "professionals".
This stems from a basic doctrine of the Church that the Church is a institution, and it is an institution made of fallible human beings. As a fallible institution, it can and will commit errors. The only way it can avoid error is for all of the church to unite together, clergy, laity. When the Church unites in this fashion, it forms the Body of Christ, and ceases to be fallible. For the Orthodox, this has only happened seven times. The last time was in 787 A.D..
If you take a doctrine that there is no single person that can decide what is "true" for the rest of the Church and add 1700 years of history, you get the Orthodox Church. Is the Church liberal? No. Is the Church conservative? No. The Church is Orthodox. Modern labels don't apply because most modern issues are just that, modern. For the Orthodox Church, the truth will become self-evident in the next 100 years or so. In the meantime, for whatever issue you're having, you can discuss it with your priest so that he can help you connect with God for guidance.
So really, the best way to learn about the Orthodox Church is simply to come talk to us.
In the meantime, here's some historical perspective excerpted from The Orthodox Church: An Introduction
The Orthodox Church embodies and expresses the rich spiritual treasures of Eastern Christianity. It should not be forgotten that the Gospel of Christ was first preached and the First Christian communities were established in the lands surrounding the Mediterranean Sea. It was in these eastern regions of the old Roman Empire that the Christian faith matured in its struggle against paganism and heresy. There, the great Fathers lived and taught. It was in the cities of the East that the fundamentals of our faith were proclaimed at the Seven Ecumenical Councils.
The spirit of Christianity which was nurtured in the East had a particular favor. It was distinct, though not necessarily opposed, to that which developed in the Western portion of the Roman Empire and subsequent Medieval Kingdoms in the West. While Christianity in the West developed in lands which knew the legal and moral philosophy of Ancient Rome, Eastern Christianity developed in lands which knew the Semitic and Hellenistic cultures. While the West was concerned with the Passion of Christ and the sin of man, the East emphasized the Resurrection of Christ and the deification of man. While the West leaned toward a legalistic view of religion, the East espoused a more mystical theology. Since the Early Church was not monolithic, the two great traditions existed together for more than a thousand years until the Great Schism divided the Church. Today, Roman Catholics and Protestants are heirs to the Western tradition, and the Orthodox are heirs to the Eastern tradition.
Christians of the Eastern Churches call themselves Orthodox. This description comes to us from the fifth century and has two meanings which are closely related. The first definition is “true teaching.” The Orthodox Church believes that she has maintained and handed down the Christian faith, free from error and distortion, from the days of the Apostles. The second definition, which is actually the more preferred, is “true praise.” To bless, praise, and glorify God the Father, Son, and Holy Spirit is the fundamental purpose of the Church. All her activities, even her doctrinal formulations, are directed toward this goal.
If you would like to read more about the Orthodox Church, the Archdiocese has several articles you may which to check out. I particularly recommend the following:
Introduction to the Orthodox Church
The Orthodox Church: An Introduction
History of the Orthodox Church