I think there is a huge demand for guns such as the PF9, LC9, and the PPS however I have yet to find one where I feel like they really got it right.
The PF9 looks like it was made in a Afghan sweat shop, the quality is horrible IMO and I've heard mixed reviews.
Ruger had the right idea with the LC9(well they stole the idea from Kel-Tec) but they ruined it with horrible safety features and the grip is pretty bad.
I think Walther has come the closest with the PPS and several members here have the PPS and are happy. On other forums though the reviews are really mixed. I would love to have a PPS but they are overpriced and the magazines are extremely expensive. Also the mag release is strange, someone also mentioned that the gun becomes inoperable if the backstraps drop out.
I wish Glock would just get over it and make a single stack 9mm.