Bateman (1998: 26):
If one goes searching for ‘holes’, then holes there are enough — indeed, Martin already draws explicit attention to most of them himself, in some cases pointing to significant possibilities for further development. For English Text, however, it is the pattern of the fabric of discourse semantics as a whole, and how that pattern can be uncovered, that counts. This is already an enormously valuable contribution to the field. Moreover, with the richly exemplified and detailed introductions to the areas discussed in the book, the questions raised by English Text establish entire research directions in functional and other linguistics for the coming decade, encouraging combinations and interactions of areas that had previously not been at all evident. The book thus provides not only a crucial text book for students but a substantial research agenda for the semantics of discourse for some time to come.
 To be clear, Martin, like Bateman, is completely oblivious to the theoretical inconsistencies that arise from his misunderstandings of Halliday's and Hasan's work, as set out in detail here.
 To be clear, what is "already an enormously valuable contribution to the field" is the original research work carried out by Halliday and Hasan on SPEECH FUNCTION and COHESION that Martin has merely misunderstood and rebranded as his own systems of NEGOTIATION, IDENTIFICATION, CONJUNCTION and IDEATION, as previously explained on this blog.
By not bothering to check the provenance of "Martin's" ideas, and not being able to assess their consistency with(in) SFL theory, Bateman has witlessly colluded with Martin to defraud an academic community and waste the research potential of generations of students.