Nice tool, nice approach and very simple in use.
No doubt, there are more sofisticated renamingtools out there for example, but most users will find what they need, I think.
The nice thing is the approach:
What happens after we took images with our digital camera ?
We download them to our mac, they all have a number which is telling us nothing, we like to group them in folders, we like to make albums, carts etc in iPhoto...
The interface can be more flashy.
I wish the MoonApp team lots of energy to continue there, quit new, product.