If only all bugs were fixed - quite a few are not fixed since long time - e.g.: https://github.com/websharks/s2member/issues/1039
Many others that actually are about core functionality are open on Github too. I really have the feeling nearly no website with large paying userbase relies on s2member - else they would be closed or more complaints/reports. Are there any websites using s2member for checkout/usermanagement that have 6 digit €/USD turnover per year? I don't believe more than a handful, if at all. Else invoicing, user payment history, UI on frontend/backend would be much better. Functionality for a website that scales and actually sticks to VAT laws now present in not only EU, but also Russia, Japan, India, soon Australia/China and so on would be there (soon every big country except USA will have stringent VAT requirements except USA - and starting with first dollar/euro/whatever spent by one of their citizens). Even if you connect Quaderno or Octobat into your Stripe account paying VAT will be random due to the address country bug...
Yes VAT is super complicated - even more as different products require different rates - but with s2member you cannot even get full VAT support through external providers due to bugs (Stripe) or missing information (Paypal) in an automated way.
It's great that s2member has loads of features - but to me many of them don't seem to be working all the way - most things work for 90% of cases but there are quirks here and there and some of the functionality interferes with other functionality.
And the main feature for the pro version - the checkout - gives a UI that is really really tough to understand for people checking out. Lately also more and more combinations of browsers/antivirus and so on that block Stripe from working - especially if you have address check enabled - via old way of setting tax - then there are loads of combinations now that stop the user from checking out.
PHP7.1 warnings are another thing - little things popping up here, then there which show that codebase is really old. In 2012-2013 s2member promised a completely revamped s2member (mostly called new major version or release) - it never appeared however. -- nothing promised here ever arrived:
besides the ability (quite complicated) to show the user his EOT (if set - however e.g. not when his next subscription payment is due). Also still no information about any of the other features like payment amounts/times.
Basically instead of a nice backend where your customers can have an overview of past/future payments, EOT and invoices - things that are simply expected nowadays if paying online for services/products - don't exist and it's really really difficult to implement. As website owner running s2member I have to rely on gmail search function and s2member notification emails to actually backtrack user history (and yes - that's essential - far too often customers think they bought something, wrongly remember what they bought and so on - forgetting their username, email used, passwords and much more) - but the only way to research this is going through email notifications by s2member - as there is no history also in backend about the user and his purchases.
Yes that's many many things, but on other membership/ecommerce platforms they do exist - even though you have to buy them via additional plugins. That's still way cheaper than hiring a developer to code your one off solution for s2member (within 6 years of using s2member - I ended up paying nearly a 5 digit € figure for s2member fixed/custom addons to external programmers - simply to get it working somehow - actually only getting features which would be available on i.e. wocommerce or EDD as addons). In the end s2member pricing IMHO is way to cheap to deliver a fully working and supported professional product. With S2member pro being a onetime buy, and not a yearly amount - they cut of their income. With wocommerce membership, EDD and so on - I guess most people end up paying 200-500USD yearly for licenses/add-ons. No wonder newer wpshark plugins are not a one time buy lifetime updates model anymore.
If s2member had cleaned their code and kept adapting it to modern web/wordpress standards, and opened up an add-on store many years ago - I guess the situation could be really different. Lot's of backend functionality - but missing on the frontend/UI/simplicity a lot.
When I started using s2member in 2011 it was one of the best solutions - and even looking back there would have been only one or two other plugins that would have worked out much better in the long run. But changing to another membership plugin if you have thousands of users is really really difficult/expensive. I'm not sure how long until I will end up paying a big big sum to convert however.
Maybe s2member should be officially discontinued and a new more expensive but well supported and modern successor should be built. If there are actually still people making money using s2member they will pay for it. Maybe based on woocommerce as so many of the things that are missing in s2member are available there as addons.
e.g. for me also supporting Stripe sources besides Credit Cards would be a must: https://stripe.com/docs/sources
(and invoicing/user payment history, clean account for users to login to find out all info about their account, and actually an easy 1 click and configurable checkout would be really needed. Wocommerce would be 2 click due to cart nature - but the UI is very good so that would be okay too)