It does have very flexible metaprogramming capability and the syntax of the language can be extended in the language itself, very much like Lisp, and like Lisp it has a high skill ceiling and a huge possibility space to explore.
It's the ways in which it is not like Lisp, the features that Lisp hackers discovered decades ago were nests of bugs and confusion that... arghhh.
My overall impression of Tcl, however, is quite positive -- and Tcl/Tk is a JATO bottle for rapid GUI development that no Lisp implementation has yet been able to match -- not without embedding or incorporating Tcl itself (e.g., PS/Tk: https://wiki.tcl-lang.org/page/PS%2FTk).
It's the ways in which it is not like Lisp, the features that Lisp hackers discovered decades ago were nests of bugs and confusion that... arghhh.
My overall impression of Tcl, however, is quite positive -- and Tcl/Tk is a JATO bottle for rapid GUI development that no Lisp implementation has yet been able to match -- not without embedding or incorporating Tcl itself (e.g., PS/Tk: https://wiki.tcl-lang.org/page/PS%2FTk).