My fear w/ subscriptions is that once you are locked in, it is time-consuming to get out. So, I, always, try it out.
Almost went for Amazon Prime (middle of this year), but, the 3rd time (re-ordering my 2 boys' food) found the price had gone up to Petsmart's price. So, shopped (again) &, now, with Chewy.com (last 2 months).
My daughter has Prime and she swears by it. So, there is the 2 sides of the coin (in the same household) :-)