I just recently bought my first polymer gun, an FNP45. I was of the "plastic? NOOOOO" group for a long time, and then I realized that polymer semi autos have been around and succesful for quite a while. That FN's parts are mostly polymer and stainless steel, and I was looking for a tool, nothing more. That gun is exactly that, a tool, and a seemingly durable one that I believe will give me years of reliable service. I plan to purchase a Ruger LCR for pocket carry sooner than later. I think the manufacturers know what they are doing, and that gun has been on the market for a while now. I plan to get the .357 version, because like the FN, it is made of stainless steel and polymers, though I doubt I'll shoot many hot loads out of it. The .38 versions are made of the alluminum alloy and polymers.
I think it's really a matter of what you want the gun to be. If you want a tool that can get banged around and isn't really for looking at, then a poly gun seems appropriate. If you want a looker, then get a nice revolver or a 1911.