If one wants to know what the Orthodox Church teaches about the early life of the Theotokos, etc., then all one needs to do is to read the lengthy accounts of the relevant feasts in the Synaxarion, St. Dimitri's Lives of Saints... and the texts of the liturgical services.
Anything found in the Protoevangelion that is not reflected in these primary Orthodox sources may be suspect.
I haven't researched this in a long time, but my recollection, which may be faulty, is, as I wrote earlier, that there are divergences between the Orthodox accounts and what is written in the Protoevangelion. It strikes me as similarities born out of a common source in Holy Tradition, rather than the Protoevangelion being a part of Holy Tradition in the same way that, say, the writings of St. John Chrysostom are.
Kolokotronis may, however, be more right on this than I am. Wouldn't be the first time.
I read the Protoevangelion of James last night for the first time in many years. There is little or nothing in it regarding the early life of the Theotokos that is not found in the Orthodox accounts.
I found nothing Gnostic or otherwise heretical in it -- at least not that I was sharp enough to pick up on. There certainly is no obvious Gnostic agenda to it. There are some miraculous happenings in it that are unlike the character of other miracles in the New Testament, but they are not unlike some unusual miracles reported in the Old Testament or the Lives of the Saints.
The only thing that really raised my eyebrows a little, wondering if there might be a Gnostic influence, was a part of the account of Christ's birth where Christ's birth seemingly takes place as a flash of light (the birth itself is witnessed by no-one, but Joseph and Salome see this flash coming out of a cloud of light surrounding the cave.) It strikes me as more of a poetic way of expressing the mystery of the Virgin Birth itself, and Orthodox iconography does usually show a light coming down from heaven to the cave.
In short, Kolokotronis was right -- the Protoevangelion can safely be considered to be a document that is a part of Holy Tradition, with the usual caveat that Holy Tradition is not infallible in the sense of the individual patristic writings themselves, but rather in the context of the overall message of the patristic writings, oral tradition, liturgical services, etc...
It was readily apparent why I remembered wrong -- a number of the apocryphal books that are found before and after the Protoevangelion in that particular volume of Eerdman's are indeed Gnostic or otherwise heretical. The editors do not say that the Protoevangelion is Gnostic, but do identify numerous other of the writings as being such (and they are -- as in the "Gospel of Thomas".)