Greetings to all. I have just come across this thread while looking up something else and thought it might help if I added what I know about Elder Ephraim.
My mother is one of Fr Ephraim's spiritual daughters and he has stayed at my parents' house on occasion. He has also stayed (a long time ago now) at the Canadian home of some friends of mine who now live in England. I have visited his monasteries in Florence, Arizona and Dunlap, California as well as two of his monasteries in Greece (near Serres and Volos respectively). I also know some monks at the Athonite monastery of Philotheou, where he used to be abbot. I myself have met Fr Ephraim only once and then only fleetingly.
First of all I have no doubt whatsoever that Fr Ephraim is a devout Orthodox monk who conforms to the patterns of monasticism that have been prevalent throught the whole course of the Church. He is certainly not the leader or creator of a personality cult centred around himself: I simply have never seen any evidence of it and I have met dozens of his spiritual children. My own observations of people I have met and who know him is that he is revered primarily for his personal piety and his good council. In some cases it seems to me, however, that the reverence can be somewhat overdone, particularly by some of the lay women (never any of the monastics) I have met. In that sense he may, perhaps, be considered a cult figure, but this has nothing at all to do with Fr Ephraim personally, but is rather an immoderate reaction to someone with exemplary qualities.
Rarely mentioned on the 'net is Fr Ephraim's role in rejuvenating the Holy Mountain. In the 1960's there was talk about the sad decline of monasticism on Mount Athos: about the old age and decrepitude of the monks and the decline of numbers in the monasteries. The reason Mount Athos is thriving today is ascribed to the influence primarily of Fr Ephraim of Philotheou and Fr Aimilianos of Simonopetra. (See for example "O, Holy Mountain" by Fr Basil Pennington, a Catholic monk who stayed at Simonopetra in the 1970's. He mostly talks about Fr Aimilianos and does not actually meet Fr Ephraim but he does talk about Fr Ephraim's influence.)
Perhaps the difficulties that Fr Ephraim is having in some quarters in the United States is the type of monasticism he exemplifies. On Mount Athos some monasteries are very strict about some matters such as attendance at services and the presence of the non-Orthodox in church while others are less so. Fr Ephraim's monasteries on Mount Athos (and at least four have been directly influenced by his example) are the most strict.
Fr Ephraim's monasteries in America, naturally, reflect this pattern of monasticism and this does not go down well in a country which is not used to monastic (or, indeed, other sorts of) discipline. Actually, I myself, am not totally comfortable in Fr Ephraim's monasteries and I prefer the sort of monasticism that one finds in Simonopetra and Ormylia, which are monasteries influenced by Fr Aimilianos, but I have no doubt that Fr Ephraim's monasteries have a valid form of monasticism.
I do think that Fr Ephraim is making a tactical mistake in making his American monasteries so very Greek, but I am told that his reason is that he knows how to set up a Greek monastery with all of its services, disciplines and routines and that he has no objection to more English speaking and 'American' monasteries, but that this is a job for someone else who would know how to do the job well.
Nonetheless, services in English would help to ameliorate the alienness of Orthodox monasticism, especially to those who tend to think of Mother Theresa when they are asked to think about monastics at all. (And I include some Orthodox priests, whom I personally know, in that category.) I'm sure that some of the difficulties are caused by people thinking that Orthodox monastics should somehow conform to the very different, western view of what a monk or nun should be.
Sorry for having gone on so long, but I hope that my contribution helps someone at least.
Yours in Christ
Dorotheos