The problem is, to put it simply, Anglicanorum Coetibus, (the Apostolic Constitution , "AC") is not a vehicle for unity of Anglo-Catholicism and the Roman Catholic Church; yet a lot of people seem to think it is.
One reads of devout men and it has to be said, on the whole Clerics, that they have "always believed what the Roman Church teaches." Members of the TAC particularly state that by their Bishops signing the Catechism of the Catholic Church, proving de facto their adherence to Roman doctrine, that therefore it is only natural for them to seek unity with the Holy See.
The trouble with this is that a) if they truly believed what the Roman Church taught, they would've converted to Rome years ago surely and b) by "uniting" with Rome under the terms of the AC, they are in fact only submitting/being received as Roman Catholics - not Anglo-Catholics - and if they have always believed what Rome teaches, they will be bringing nothing with them but what is "cultural" of the Anglican Patrimony.
The truth of the matter is, Anglicanism has never taught the same as Rome - some Anglo-Catholic clergy have taught Rome's doctrines, true, but no official Anglican Catechism has ever taught the Immaculate Conception, the Assumption of Mary and most especially not the Infallibility of the Pope!
The Apostolic Constitution should be understood to be what it is - an opportunity for Roman-thinking Anglicans to be received as Roman Catholics. What it is not, is an exercise of unity between Anglican Catholicism and Roman Catholicism. What is unclear, especially from the statements of TAC members is, that if they have always believed the same as Rome teaches, what will they be bringing that is "Anglican" except a penchant for fine liturgy and music?
There is more to Anglican Patrimony than that which is just cultural - but the apologetics and theological discourses of the Homilies, the writings of the Divines etc are not being offered by the TAC - for they have "always believed" what is stated in the Catechism of the Catholic Church and that is not up for discussion... This is not the result nor the conclusion of the ARCIC dialogue (Rome has made that clear) meaning that it is not therefore "the meeting of minds", the long awaited "agreement" between Anglicans and Romans on doctrine and theology and understanding. This is simply the reception of Anglicans as Romans.