As for whether the Orthros is a good first service to attend: that depends a lot on the parish, and a lot more on you.
The Orthros is a beautiful service comprised of several unchanging elements, mostly Psalms, which form the skeleton of the service, on which are hung the thematic hymns for the day, for the tone of the week, and for the liturgical season. When you understand the language in which the Orthros is done, it is an immediately accessible prayer service that exemplifies the way the Orthodox Church approaches corporate prayer--that is to say, the prayers/psalms/hymns are read or sung, expressing sentiments of joy, repentance, humility, honour, thanksgiving, etc, and each person present endeavors to enter into the spirit of the prayer of the Church, taking the words of the Psalms or the hymns as one's own and offering them to God.
However, despite all this, the Orthros is often the most inaccessible service, for several reasons. For one, it is a technically complex service, and often the chanters/choir struggle in the task of leading the people present in an effective way. It is very easy to mumble when reading a psalm, or to screw up while chanting a hymn, even if you have a clear idea of what you are trying to do and what your responsibilities are as a servant of the Church and her life of prayer. For another, often the Orthros is given over to a single chanter, who is often elderly, and therefore struggles all the more because his voice and eyesight are failing. Finally, as a corollary of the previous point, because this elderly chanter was trained only in the Greek language, he often chants and reads only in Greek, making the service still less accessible to the visitor.
However, the service can still be deeply edifying, if you are able to either follow along in the service book (if the church provides one), or simply take the opportunity to offer your own prayers to God over the course of the service. I simply mention the above because, having made the journey myself from Protestantism to Orthodoxy, I know all too well that there are several elements of the Orthros as commonly done in the parishes of the Greek Orthodox Archdiocese of America that make it difficult for the visitor to discern the simple, humble, prayerful beauty of the Orthros, particularly in the beginning.
I hope this is somewhat helpful, either to the OP or to any others.