What unforeseen dangers might exist when choosing an open access textbook for a new subject?

I must create a new module (first time to do from scratch). In the past, I've had either existing course descriptions, textbooks, etc. as a base on which to structure a module which is new for me. This time, I have nothing (blank canvas).

My thought is to use an open access textbook and some initial looking makes me believe I can find something either usable as-is or that will allow me to mix-and-match the chapters into something suitable.

I'm concerned about what, if any, dangers might not be obvious to me at this stage but might cause significant problems for the students, myself, or the department later (say, after the semester begins).

After reading this question, I still find myself wondering.

If anyone has designed a course using an open access textbook in the past, what are the key considerations which should be considered for first-timers?