The G19c is the compact 9mm, with factory ported barrel and slide. I got this on the recommendation of my brother, Jeff, over at J&Ds Essentials. I watched a review video on youtube, and decided to give it a go.
My first impression was that it looked... well, damn cool. You notice the ports in the slide right away. I took it out shooting with some friends, one of whom was a new shooter. After warming up with the trusty ole Buckmark, she wanted to try out a 9mm, so I had her give it a go on the G19c. It wasn't long before she was punching holes in center mass of the target. I shot it a little that day, but was mostly focused on getting used to the trigger (which was a little gritty).
The second time I shot it was at Rock-n-Thunder, an indoor shooting competition at Thunder Alley here in Lincoln. To make a long story short, I placed 5th with the G19c and something like 16th with my XDm! I was amazed at how accurate the 19 shot. The porting makes the gun shoot an awful lot like a .22 (no, really).
I've since shot it several times and have started carrying it as my primary EDC (everyday carry) gun. The smaller grip makes it easier to conceal than the XDm.
So, if you get a chance to shoot a 19c, do it. My only "complaint" is that cleaning takes a little longer because the slide and barrel dirty pretty quick.
I've since read that some people don't recommend carrying the 19C because the vents in the slide allow muzzle flash to go upward into your field of vision. I haven't shot it at night yet, but am anxious to do so to test out this theory.
Update: So I had the opportunity to shoot in a low-light setting this week. The muzzle flash was certainly NOT blinding. I could see it, but was able to still clearly see the target at 5 yards.