When I found this extension I was searching for a thin and easy-to-use possibility to built templates for articles. And that's what I get with n3tTemplate.
It was important that the other users, which dont't have any knowledge and understanding of programming, can use this extension easily and intuitionally; and they love it :)
I use Joomla 1.7+ for my project. The installation is easy and works without any problems. The support is fantastic though it's non-commercial.