To understand the importance and the future of Tcl/Tk I strongly suggest to point your web browser at the URL www.scriptics .com/people/john.ousterhout/ by John K. Ousterhout . You will read about the importance and the comparison between scripting (in langua ges such as Tcl) and system programming (in languages such as C and Java).
To read a document about comparisons see the comparison discussion.
Here's a summary of the most important pros and cons about Tcl/Tk.
The data is primarily treated as strings, programs written in Tcl are slow. Tcl 8.x attempts to address this by doing some degree of compilation as well as permitting additional variable types.
Comments are commands rather than traditional comments, numbers beginning with 0 are octal, proper use of quoting mechanisms, etc. These aspects are covered in the various FAQs.
You need to write a lot less code to get your job done, especially when compared to Motif or Win32 applications. In general, the number of Line Of Code (LOC) of a software project is one of the most important complexity index es.
You can get the sources for free over the Internet from Scriptics Download Page or from the FTP site for Tcl. The software c ore site includes the source code version, as well as binary versions for Windows and Macintosh platforms; or, you can get Tcl on a number of CD-ROMs for a nominal cost.
Read about Tcl and Tk core free at www.scriptics.com/about/n ews/qa.html .
Versions exist for UNIX (Linux... of course), Windows and Macintosh. Except for a few platform differences, your Tcl scripts will run the same way on all systems.
You can execute your code directly, without compiling and linking (though Tcl compilers are available).
It's easy to add your own commands to extend the Tcl language. You can write your commands in C or Tcl.
The Tcl interpreter is merely a set of C functions that you can call from your code. This means you can use Tcl as an application language, much like a macro language for a spreadsheet application.
Read what the creator of the Tcl and Tk core tells about this topic www.scriptics.com/Y2K.html .