How to review a major revision of a paper? A few months ago I reviewed my first paper. The authors submitted a major revision and I am asked to review the paper again. I received a long cover letter where my comments and the comments of two other anonymous reviewers have been answered.

The paper is relatively long (40 pages) so I am trying to avoid unnecessary work. Should I:


Re-review the entire paper as if I saw it the first time,
Just check if all comments have been addressed, or
Just check if my comments have been addressed?


I am afraid that if I just check the comments, it is possible that the authors have made some other changes, or that their changes might have broken the integrity of the paper as a whole. On the other hand if I re-review the entire paper it might be unfair to the authors.
When a major review has been requested, I think you really do need to go through the whole paper, for exactly the reasons you cite—the changes you've requested may conflict with the changes another reviewer has requested, and therefore the authors may have had to exercise significant discretion on which one to formally include in their revisions. Similarly, there may have been other changes that arose from your comments or those of your fellow reviewers. 

Minor reviews require a lower level of commitment, unless the authors have indicated more substantial changes have been made.