This 1.5 version includes 3 new features that may be very useful for your Magento website:
A new customers import/export module
You may now export your customers and product from Magento backend with an advanced attribute filter feature.
The good old dataflow profile feature is still available.
Order State and Status can be modified from Magento backend
Now you don't have to edit XML files to modify order state and status as this can be done from the backend.
Modify order adresses after an order has been made
This will be very useful to customer services: you may now edit an address without having to create another order.
Be careful though: this will not recalculate order amount nor shipping fees.