I like Subscribe & Save with two major exceptions, which stops me from using it:
1) Things go out of stock too much if it's a little more specific.
2) Prices are very sporadic and unstable. A subscription should be relatively predictable - with the exception of the obvious price inflation over time, but I'm talking month-to-month.
When you subscribe to something it doesn't "lock in the price" - prices go up and down month-to-month.
On the amazon side, there seems to be a bit of flex built in, when they'll still tell you the item is in stock, and tell you the price before the re-buy kicks in.
A lot of the items I "get told are unavailable, would I like to go with the alternative?" are still available, just for a higher price.
i.e. I think a lot of the "annoyance" is actually amazon bulk negotiating on your behalf. If say P&G decide to raise their price on their detergent, amazon has the power to decide whether 90% of their customers swallow the increase, or they all find an alternate brand.
My guess is that amazon decides not to provide P&G detergent to a few hundred thousand subscribers in a month, that helps 'focus' the P&G rep in getting the price back down the next month.
1) Things go out of stock too much if it's a little more specific. 2) Prices are very sporadic and unstable. A subscription should be relatively predictable - with the exception of the obvious price inflation over time, but I'm talking month-to-month.