Ghost Reveries is such a weak album. There's like only 3 good songs in it (Ghost of Perdition, The Baying of the Hounds,Isolation Years). No idea why some could claim that it's the best album of Opeth. If I were to rank their album (excluding Damnation which is totally different) it will go:
Blackwater Park
Still Life
MAYH
Morningrise
Watershed
Orchid
Ghost Reveries
Deliverance
I think Watershed is a decent album, nowhere near as good as the 3 Opeth classics but still much better than Ghost Reveries and Deliverance. Since Blackwater Park they have really struggled to find their new sound, and both Ghost Reveries and Deliverance are poor efforts from one of the most talented bands out there. And I do think that they have found something with Watershed. I sure hope that they can built on it and make something really good next.