It is a great tool which you can use for building all you need for creating and managing website applications. I have used it for creating an exam sessions booking system. Without using this component I don't know how I would have been able. All I had to do is just to set few table, with 3 words of php.
The effort and time cost have been decreased incredibly, although it was the first time I have used this component.
as time goes I was thinking that with this tool it is possible to create anything.
I'm waiting for the stable 2.0 version for using with Joomla 1.5