The Smith & Wesson SD40 is clearly a statement by the American heritage firearm company against the popularity of the Austrian Glock.
The SD-40 is a striker-fired pistol with a polymer frame that is between the Sigma and the M&P models in reference to features and price. It is chambered for .40 S&W and the SD9 is chambered for the 9mm, for those who prefer the latter. Both models are available in the standard capacity magazine or low capacity magazine (for states that limit magazine loads).
The SD40 holds 14 cartridges and its magazines are allegedly (I did not personally try it) interchangeable with the Sigma. Melonite coating is on the stainless steel slide, just like the M&P models. Thus far no complaints about how much the coating can take.
The SD40 has an accessory rail for laser, light, or whatever. It has a good and functional magazine release button and has a ridge so it is not accidentally pressed. It is not ambidextrous, however. Even the slide is not designed for left-handed shooters.
A feature that law enforcement officers like and asked for: loaded chamber indicator.
When field stripping the SD40, it is like the Sigma and the Glock; and uses a captive recoil spring. The closer the range, the tighter the group; but at 25 yards the accuracy is excellent.
If you want the trigger to operate more smoothly, it will have to be done at a gunsmith shop; it is heavy as the Sigma and some may not like that.
The MSRP is $389-$459.