IMO yes, one it's quicker, two the kestrel is pretty rugged. Yes you can buy a lifeproof case or something like that for your phone, but I like how the kestrel is always updating as well. It's nice to point it at a target, point it at the wind, and boom you have a solution.
Also, most places I shoot don't have great cell service, so I notice my phone is often going dead quickly. A solution to this would be putting it in airplane mode.
Bottom line, both systems work, as someone who's used both, I like having the Kestrel with the AB or Horus app built in as it's quicker and easier to use. Fumbling around with a lot of gadgets can be a pain in the butt in the field.
I hope that answers your question.
DG.