1. For tax returns reviews. This will save a whole lot of time.
2. Once return is printed, it is so much easier to navigate, especially in 100+ pages. To easily find Federal and Tax forms. 
3. I can bookmark pages that need to be signed (manually or digitally).

4. If client calls to go over specific item, it would be so much easier to navigate in pdf file.

5. Compare to the prior year returns.

6. It looks professional (even TurboTax provides this feature!).