Attitude/Tone questions can be tricky - there's certain words and types of words you want to look out for. My favorite thing to spot is adverbs - if the author in a passage says "The researchers concluded that A is true," that doesn't show attitude; but if the author says "The researchers, unwisely
, concluded that A is true," or "The researchers, happily
, concluded that A is true," those indicate how the author feels about the researchers' conclusion.
Adverbs are one good thing to look for. In this passage, the approval is best found in the first paragraph, where the author describes the book as "contribut[ing] significantly to a recent, welcome shift". The approval is qualified by the author noting that Breen and Innes underemphasize some things: here, "qualified" means "with limitations," so their approval comes with acknowledgement that the book is not perfect.
I can see how you got a challenge out of that, but this passage as a whole doesn't really oppose the book strongly enough for this to be a contentious challenge. Overall, the author seems to approve of the work, though he/she has concerns about it.
Hope that helps,