Depends. Most physicists look at it like some people looked at Darwin's theory of evolution back then...completely retarded. Some look at it as a stroke of genius. I'm no physicist, but I think that the string theory is highly credible. The only reason why physicists disapprove of the string theory now is because no one has came up with any legit proof yet. It is just in it's idea stage. Not enough ground-breaking tests have been run.

It is starting to become a valid theory. Many scientists are working on it. www.pbs.org/wgbh/nova/elegant/

Yes. There are still many cosmologists and others who are very skeptical, although string theory is looking more and more like an acceptable theory. The problem with acceptance of string theory is that it's all mathematics and almost no experimental verification at this point. That gives most physicists the willies! Heh!

Yes. As I understand it, many physicists are impressed with the mathematical elegance of string theory, and the way that many inconsistencies in our understanding of the Universe get resolved by string theory. However, string theory has not (yet) produced a testable observational prediction, where scientists can fire up their colliders, look at the results, and say "Yes, this indicates that string theory is likely true". To many scientists, the lack of testable predictions means that string theory is not science in the strictest sense.

I would not use the word "derision". "Although string theory is an outgrowth of physics, some contend that string theory's current untestable status means that it should be classified as more of a mathematical framework for building models as opposed to a physical theory. For a theory to be physics, it must be corroborated empirically, through experiment or observation, but few avenues for such contact with experiment have been claimed. - Is string theory falsifiable? Following the appearance of two books claiming string theory is a failure, a hot media debate evolved in 2007. "For more than a generation, physicists have been chasing a will-o’-the-wisp called string theory. The beginning of this chase marked the end of what had been three-quarters of a century of progress. Dozens of string-theory conferences have been held, hundreds of new Ph.D.s have been minted, and thousands of papers have been written. Yet, for all this activity, not a single new testable prediction has been made, not a single theoretical puzzle has been solved. In fact, there is no theory so far—just a set of hunches and calculations suggesting that a theory might exist. And, even if it does, this theory will come in such a bewildering number of versions that it will be of no practical use: a Theory of Nothing." The controversy centers around two properties of string theory: It is widely believed that any theory of quantum gravity would require extremely high energies to probe directly, higher by orders of magnitude than current experiments such as the Large Hadron Collider. String theory as it is currently understood has a huge number of equally possible solutions, called string vacua and some scientists believe that these vacua are sufficiently diverse to explain anything. If these properties are both true, string theory as a theory of everything has no predictive power for low energy experiments, and would probably not be falsifiable by any current or future experiments. Because the theory is so difficult to test in the foreseeable future, some theoretical physicists have asked if it can be called a scientific theory, as it is not yet definitively Popper falsifiable. String theory does predict, at least perturbatively, that at sufficiently high energies—which are probably near the quantum gravity scale—the string-like nature of particles should be apparent. For example, there should be heavier copies of all particles corresponding to higher string harmonics. However, it is unclear how high these energies are. In the most likely case, these energies would be one million billion (ten followed by fourteen zeros) times higher than those accessible in the newest particle accelerator, the LHC. This would make it very difficult to probe string theory directly." Source and further information: http://en.wikipedia.org/wiki/String_theory#Problems_and_controversy