All Tolkien is out, and all Perumov is in, and what started as an honest effort at Tolkieniana becomes an average epic fantasy with shades of swords-and-sorcery. Mind you: the location in which the action takes place is only called "Middle-earth"; it has no other relationship to Tolkien's secondary universe, despite the presence of Dol Guldur, Valinor, Rohan, etc. The coincidence in place-names and other geographical details is purely accidental. :)
That said, standing on its own, it is not a terrible book (despite some seriously unbelievable action scenes). But it is not a standalone work: more of a link between Perumov's early Tolkien pastiches and his later stories set in Hjorvard, and as such, of little interest.