In my reading around the topic of the Jesus Prayer I have noticed a few things that stick in my mind.
Firstly, both Abouna Matta el Meskeen and Lev Gillet (the Monk of the Eastern Church), consider that the Eastern Orthodox spiritual tradition has become too systematised and professionalised, and that this is a bad thing.
I have tended to agree, as far as my opinion has any weight at all. I have been on many Eastern Orthodox forums where Christians are being told that they should not develop any sort of prayer rule without an experienced spiritual guide, and that they should not dream of praying the Jesus Prayer as it is bound to lead to disaster.
Matta el Meskeen and Lev Gillet point to the Jesus Prayer becoming the subject of discussions about the right words to use, and they suggest that the Eastern Orthodox spiritual tradition in the middle ages lost the flexibility and vitality which was the hall mark of the earlier period of spiritual teachings.
Certainly in my own readings I see that there were a wide variety of phrases being used as short prayers to keep the mind and heart focused on God, and in the Deserts they especially used 'O God makes speed to save me, O Lord make haste to help me'.
Secondly, in my own reading I have noticed a tendency in the later Eastern Orthodox tradition for their to be a focus on spiritual results, such that I have read Eastern Orthodox Fathers who explicitly state that the end of prayer is the vision of the uncreated light, and who even provide teaching about what is the quickest and easiest way to see this light.
I found, and still find, such an emphasis problematic.
On the other hand, I am grateful for a more earthy tradition from the Deserts, and of course from many other writers, both EO and OO, which describes spiritual results as an uncalled for gift, and all spiritual exercises merely a preparation and duty, not a means to an end.
Yet there is a danger in that such an earthy view becomes simply moralistic. And I have seen in some places an understanding of theosis/deification as simply 'doing what is right', but doing it more and more. I cannot accept a moralistic view of the Christian spiritual life any more than a systematised one.
I hope that there is a solid middle ground in which the spiritual ascesis is a right response to God, but does not demand anything in itself, but lives in hope. And that the true theosis is that living in the grace of the Holy Spirit, which is the renewal of our humanity, and is the gift of God Himself to us.
St Seraphim of Sarov seems to me to have it right when he says that the end of our life is to acquire the Holy Spirit, and he is not acquired by a system, or by merely being moral. Indeed he is the giver of gifts and the gift himself. A gift is not deserved, but it is received with thanksgiving.
I would like to see us make more of the Holy Spirit, as increasingly I believe that my Christian life is essentially and fundamentally life lived in the Spirit or it is not true life at all.
I have sense some differences among some EO. A real hesitancy to say that the fulness of the spiritual life is for all, a real fear of encouraging ordinary folk to seek such a life. That is why I enjoyed Orthodox Prayer Life so much because it encourages ordinary people to aspire to a deep spiritual life in Christ. On the other hand, the Roman Catholic work which was translated and edited into Russian Orthodoxy as Unseen Warfare is brilliant because it is also practical and open to all. But it seems to me that Unseen Warfare also avoids the spiritual systematisation of the middle ages in Eastern Orthodoxy.
There is something wrong when I read a convert EO hesitating to develop a spiritual life because he has no spiritual guide. Of course there is a danger of being deceived and of becoming prideful, but I always think of the passage where our Lord says, 'who among you if his child asks for bread will give him a stone'. But there is also something wrong when young OO think that holiness is a matter of avoiding certain activities.
I hope that we can find a common tradition which still exists in the EO and OO and which is rooted in the Soteriology of St Cyril. There are discussions and controversies about this subject in the Coptic Orthodox community but I do think that as Marc suggests, this is partly because some Copts have merely taken the medieval development of one aspect of spirituality in the EO and tried to present it as being the continuous tradition of the OO. I am not sure that it is. But behind both there is a genuine spiritual tradition which is still present in the EO and OO, though sometimes neglected as not being sophisticated enough.