That's neat, but without closures I don't really see how you could do much with it outside of toy examples. Going off the examples -- how often do you write something like a foreach or a map or reduce that doesn't reference its enclosing scope?
GCC supports it http://gcc.gnu.org/onlinedocs/gcc/Nested-Functions.html
Some high praise, that. C++ closures: they're not that awful.
I would argue the opposite: these things are actually way more useful than they seem at first. The fewer things the language makes you think about, the more you can focus on what you're trying to actually do.
If you want a language with closures, and all you have is C, the time-honored solution is to write an interpreter and give the interpreted language closures. That is a good way to go.