I would agree that one major point is that InDesign comes with CS3, so you're buying Photoshop and Illustrator anyway, so ID is included.
There is also excellent integration with the other Adobe apps -- drag and drop support -- and you can import native PSD files. Combine this with Adobe Bridge and you have a seamless workflow.
In terms of printers taking Quark or InDesign, both programs can export to PDF or Postscript, with all printers can take, so that's not really an issue.
For new users, ID is very similar in function to Photoshop/Illustrator, so the learning curve is relatively small in comparison.
There is also excellent integration with the other Adobe apps -- drag and drop support -- and you can import native PSD files. Combine this with Adobe Bridge and you have a seamless workflow.
In terms of printers taking Quark or InDesign, both programs can export to PDF or Postscript, with all printers can take, so that's not really an issue.
For new users, ID is very similar in function to Photoshop/Illustrator, so the learning curve is relatively small in comparison.