I love this extension. In moving our site to a membeship system I purchased all the available membership components and this extension exceeds them all, working perfectly with the Joomla ACL, allowing it to seemlessly link up to any other extension. Other subscription components advertise 'plugins' to connect to other extensions for which there is really no need for now with Joomla.
Price aside this extension far exceeds other similar components. Considering it comes at a fraction of the cost makes it pretty much the only option in my eyes.