I've installed Image store and just did a test purchase for a downloadable file and hte payment went through without any problems, but...
1. I did not recieve an email notification from my site that a sale was made. (wordpress owner email or buyer email) just recieved a Paypal notification
2. There is no sale registered in the admin panel Image store > Sales
3. There appears to be no way of downloading the file purchased despite using both secure and non-secure galleries.
4. on a side note... When adding images to the cart, a page shows with HTML code after pressing the add to cart button. However when you click back in the browser and then click on the the shopping cart link/button the item added successfully.