Glock's new 4th generation frames are trickling out onto market, and I must say, contrary to what alot of the net has to say, it's an step in the right direction. The stippling is finally effective, in fact, it is down right aggressive.
The cocking serrations are easily the most obvious change from the traditional straight serrations. Like the M&P the serrations work quite well. They bite into your fingers, which is what they SHOULD do. The older Glocks, Kimbers, etc. that have wide spaced straight serrations are prone to slipping with either cold hands, or slick hands (blood, water, sweat, etc.). They aren't sharp enough, and they aren't deep enough... the new 4th gen solved both issues.
To put it simply, Glock purists will scoff, but those that want a defensive pistol that just down right works... the 4th Gen is the next step towards perfection.