It's been around for a few years, and I'd definitely recommend it. It's very comforting when you find yourself saying "Wait, what if I need to do refunds or dunning emails? Oh, that's already handled." I've saved many hours of development time by starting with it as a base, and would recommend it to anyone writing Rails-based SAAS.

It has a few wrinkles though, mainly from being actively developed in 2008, with mainly bugfixes and Rails 3 support coming since then. The main ones I'd highlight that tripped me up:

- Expects payment gateway authentication credentials to be stored in a YAML file in source control instead of loaded from the environment.

- A number of the controller actions trigger immediate email sending, which can cause customer-visible 500 errors if the email sending fails and is a less reliable way of making sure the email gets sent.

- Use Stripe API v1 instead of the current v2.

- A lot of the customer email templates are kind of boilerplate-y and would not win the Patrick McKenzie stamp of copywriting approval. I believe they're loaded in from the gem rather than from the app.

My main piece of advice would be to vendor the entire gem right off the bat -- you're likely going to be tweaking several different parts of it, and there's almost no active development that you'd have to incorporate.