I started using OSE Credit with modest expectations and to some extent it responded to them. A few major or minor bugs here and there, but nothing that OSE instant Support could not solve. Then I started to thoroughly integrate and test the component to my clients' website (an online magazine), in which point I started getting more and more disappointed by OSE.
A few examples to make my point more clear:
1) The components' integration with the default Joomla vote plugin was not predicted or tested, and as a result one could evaluate an article without having read it. When I requested OSE's support on this, they told me I should pay them to have it fixed, as it was not a very common demand (thus, they weren't feeling that obligated to fix it).
2) I was trying to make some changes to the Credit Plans I had created and there weren't being saved. In that point they informed me that the features I was trying to configure, which are advertised as two of the many OSE Credit features, were actually experimental and would work in the future. Well it surely didn't give the impression of an incomplete function to me when I was purchasing the component, or when I was actually seeing them as two more sets of options in the credit plan's page.
Moreover, there is a lack of basic features, as an e-mail notification to the administrator for new orders, or the ability to see if a user has made an online (via paypal) or an offline (via bank transaction) order. And bugs, such as granting the credits a member has bought even after the order has been refunded.
In conclusion, OSE Credit has great potential and instant support, but "instant support" doesn't always mean that your problems are solved.
Right now, I still feel terrified with the idea there might be still a few bugs left that I haven't discovered during my thorough tests - a fear that shouldn't exist to that extent with the use of a commercial component.
So until its' great potential is reached, I wouldn't recommend it for a serious, commercial website.
PS: Components' Back-end administration is not that responsive. I couldn't really work on it with a screen smaller than 10 inches.