3rd edition added marathon pace for non-marathon training plans. I get that lots of people like marathon pace for longer runs as a sort of tempo effort, but this is inconsistent with Daniels' overall philosophy of "never run in an in-between zone" since, based on his prior work, marathon pace does not hit any of the systems that he seeks to hit. It struck me as an attempt to try to be more current and maybe as a justification for a new edition (to bring in some more revenues).
3rd edition promotes cruise intervals over straight tempo runs. While cruise intervals are great and create the same adaptation as tempo runs, tempo runs also help with mental focus since you have to concentrate on pace while in discomfort towards the end of a 20 minute tempo run, as compared to the last cruise intervals, which doesn't feel as hard. That mental focus really pays off on race day, so I think it is a shame that he shifted the emphasis.
He dropped the table that he had in the 2nd edition that helps you figure out how fast a tempo run longer than 20 minutes should be. He was all for longer, slower tempos in the 2nd edition as an alternative approach to threshold training, and I think those longer and slower tempos (which, going to my first point, are still faster than MP, by the way) were really valuable for someone like the OP who is half marathon training. I think he dropped those in part because of the shift away from straight tempos to cruise intervals as discussed in the second point above.