SmithNut's reference to the 457 as a sleeper is very well put. It can be an excellent gun, although, yes, some people have had serious problems with it. One of the problems was with its early magazine release, which apparently tended to break. But S&W has upgraded this part, so it should be okay now. I've also seen several new 457s whose slide locks would not fully engage when the magazine was empty--this may or may not be significant.
For my part, I've been seriously tempted by the 457, mostly due to the weight savings compared with my 4516, but also due to its relatively affordable price. True, the 457 is not in the class of the 4516, but I think it still has a lot to offer.
JMHO.