toughness is a relative term. So for a veteran Servlet/JSP programmer, the exam seems a cake walk whereas for a novice it appears like the big thing on the earth. Also it varies based on what is being tested. A programmer exam tests you on the syntax where as an architect exam tests you on abstract level. So they cannot be compared for toughness with a common reference point.
I've seen on the web as well as in a couple certification books that the programmer certification was supposed to be one of the harder exams anyway, because it serves as a foundation for all other exams. So if you were comparing the relative difficulty of the SCJP to the SCWCD (assuming adequate experience in each respective areas), naturally the WCD would be easier. Of course, I am still studying for the WCD, so I will reserve my personal opinion until I take the exam!
“Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning.” - Rich Cook