Maybe both views are right
http://en.wikipedia.org/wiki/Akhenaten
"The early stage of Atenism appears a kind of henotheism familiar in Egyptian religion, but the later form suggests a proto-monotheism."
http://en.wikipedia.org/wiki/Atenism
"Akhenaten's reforms cut away both the philosophical and economic bases of priestly power, abolishing the cults of multiple deities, and with them the large and lucrative industry of sacrifices and tributes that the priests controlled."
"Initially Akhenaten presented Aten as a variant of the familiar supreme deity Amun-Ra (itself the result of an earlier rise to prominence of the cult of Amun, resulting in Amun becoming merged with the sun god Ra), in an attempt to put his ideas in a familiar Egyptian religious context. Indeed Aten is the name given to the solar disk, whereas the full title of Akhenaten's god was Ra-Horus, who rejoices in the horizon in his name of the light which is in the sun disk. (This is the title of the god as it appears on the numerous stelae which were placed to mark the boundaries of Akhenaten's new capital at Akhetaten.) However in Year 9 of his reign Akhenaten declared a more radical version of his new religion by declaring Aten not merely the supreme god, but the only god, and that he, Akhenaten, was the only intermediary between the Aten and his people. He even staged the ritual regicide of Amun, and ordered the defacing of Amun's temples throughout Egypt."
"In Year 9 Akhenaten strengthened the Atenist regime, declaring the Aten not merely the supreme god but actually the only god, a universal deity, and forbidding worship of all others, including the veneration of idols, even privately in people's homes - an arena the Egyptian state had previously not touched in religious terms."
"Aten's name is also written differently after Year 9, to emphasise the radicalism of the new regime. No longer is the Aten written using the symbol of a rayed solar disc, but instead it is spelt phonetically."