To analyze! Thanks to some youtube videos~
- If you get grabbed, a delayed Din's will save you. If you get grabbed or thrown, it prevents you from either taking any damage or been spared huge % damage because they couldn't follow up with a combo after the throw:
http://www.youtube.com/watch?v=rxw_0sXR8ds&t=10m2s
http://www.youtube.com/watch?v=rxw_0sXR8ds&t=7m21s
- Or even offensively in tandem with throws to rack damage:
http://www.youtube.com/watch?v=rxw_0sXR8ds&t=2m57s
http://www.youtube.com/watch?v=rxw_0sXR8ds&t=10m54s
- Forcing defensive options to put it into your favour:
http://www.youtube.com/watch?v=rxw_0sXR8ds&t=4m17s
http://www.youtube.com/watch?v=rxw_0sXR8ds&t=0m59s << Din's doesn't even have to hit in this scenario.
- Space control/edgeguarding:
http://www.youtube.com/watch?v=rxw_0sXR8ds&t=1m30s
http://www.youtube.com/watch?v=rxw_0sXR8ds&t=2m11s
http://www.youtube.com/watch?v=rxw_0sXR8ds&t=11m19s
- Stopping the flow of offense:
http://www.youtube.com/watch?v=rxw_0sXR8ds&t=4m11s
Peach probably would have proceeded to try and continue going on the offensive, but Din's delayed explosion gives Zelda some time to get back some footing.
And if Zelda had held shield longer, Peach probably would have been punished afterwords.
- Combos!
http://www.youtube.com/watch?v=rxw_0sXR8ds&t=5m41s
- More defense:
http://www.youtube.com/watch?v=rxw_0sXR8ds&t=7m17s
The only thing of course is overusing it will lead to certain punishment, and you have to be pretty accurate with the placement as the explosion is pretty small if you only let it charge a short distance.
And... yeah! TLDR, new Din's is infinitely way more useful. =)