<p>I am curious if anyone have used UnderC, Cint, Cling, Ch, or any other C++ interpreter and could share their experience.</p>

Long ago, I used a C++ interpreter called CodeCenter.  It was pretty nice, although it couldn't handle things like bitfields or fancy pointer mangling.  The two cool things about it were that you could watch when variables changed, and that you could evaluate C/C++ code on the fly while debugging.  These days, I think a debugger like GDB is basically just as good.