I have to admit that BlueJ is a very user friendly tool to learn about OO concepts. But as an intro to CS course, this may be hiding too much of how the systems work from the student.
I am all for making things easier for people, but I would rather have my students taking time to learn about the environment, perhaps using a simple text editor that is installed in the system and command line tools to compile their code.
The concepts they would learn would pass on to future years to come.
However, I think BlueJ would be useful to teach in the 102 class or a class that specifically teaches OO at a higher level.