I don't count myself as an evolutionary biologist, so my thoughts on
the matter those of an outsider. However, I have been amazed at the
bulletin board traffic on this matter, which in some ways strikes me
as similar to the problem of how many angels can dance on the head of
a pin (the answer is: it varies, depending on the size of the angels,
the size of the pin, and the kind of dance).
However, I feel compelled to put in my two cents' worth.
First, what is progress? It could be defined as forward movement through
time. In that case, evolution is, by definition, progress, and the whole
argument is over.
Or, it could be defined (as it is colloquially) as "improvement." In that
case, we need to ask if the earth is better off now, as a result of
biological evolution, than it was "earlier" (or not). My personal view
is that hominid evolution, and the evolution of "sapient" hominids in
particular, has been detrimental to the earth. Homo sapiens is actually
capable of totally destroying all life on earth --- and there are some
indications that we are not smart enough to prevent ourselves from doing
just that. Is this an improvement over the Jurassic?