Very bare bones
It only has 6 fixed positions where you can place blocks instead of widgets that can go on a lot of places. So if you wanted your custom block to go somewhere specific it is not really possible.
What we wanted was widget position functionality with rule conditions.
Hopefully they will improve this module.
Comment from Aheadworks:
Johan, thank you for your feedback.
Currently, Custom Static Blocks has 6 fixed positions that can be used on Home, Product and Category pages as well as at Shopping Cart and Checkout.
However, we are planning to improve an upcoming version of the extension by adding the widget positions. Hope you will like it.