I add this comment from Bhikkhu Bodhi (taken from a letter he wrote to me about Nibbana and published here )
Bodhi: On Ven. Thanissaro’s interpretation of nibbāna […]I disagree with his view that this reality can be characterized as a type of consciousness. His arguments rest on obscure verses and metaphors, to which he ascribes meanings that are not necessarily entailed by the texts themselves. In contrast, there are many simple, straightforward prose passages in the Nikāyas that speak of the attainment of final nibbāna as the complete cessation of consciousness. I do not know of any texts that qualify such assertions or distinguish between two types of consciousness—phenomenal and transcendental, conditioned and unconditioned. Rather, they assert unequivocally that consciousness arises in dependence on conditions; that it is impermanent, dukkha, and subject to change. And they say that with the attainment of final nibbāna, consciousness ceases without remainder.