I usually don't post gun reviews, but since this is a pretty new firearm and there isn't much out there...I'll give my two cents. Bottom line: if you have the cash and are on the fence about this gun, I'd recommend picking one up. Its not going to make you throw your Glocks, M&Ps and HKs into the trash, but its a hard pistol not to like.
I picked up the P320C a few days ago and just got it to the range yesterday. Put ~600 rounds through it, including 124 +P and 147g Gold Dots, 115g Federal JHP, and 115g PMC FMJ. All fed, fired and ejected perfectly. Shot it limp wristed and weak hand-only to see if it would cycle, and there were no issues. I did not get a chance to run cheap steel cased ammo through it, so I can't attest to how it likes the Tula, etc.
Accuracy was as good as any other service pistol in my hands, which is to say its way more accurate than I am. I'm not the type who enjoys shooting from a rest, but I was able to get five rounds into one small hole at 15 yards. I'm sure a better shot could get the same results from a longer distance.
One thing about this gun is that it looks much bigger than it actually is. Compared to my G19, the P320C is about the same width, a little shorter in length and a little taller in height. But bottom line, it carries just fine with a good IWB holster and a t-shirt. It reminds me of an HKP2000 as far as CCW profile goes. The bore axis had me worried initially, since I'm used to Glocks/M&Ps. But somehow, it didn't affect my shooting. Fast/accurate follow-up shots were easy.
Some things I noticed from other reviews were 1) trigger bite and 2) slide lock back problems. I didn't get any trigger bite, which could be due to my grip/hand size or the fact that I have the compact model. I did encounter issue with failing to lock back on an empty mag though. In ~600 rounds, it failed to lock back twice. It was with the same mag both times, so could be a follower issue. Or it could be my grip, since the slide release is much more pronounced than a Glock's.
The major pro that this pistol has going for it is simplicity, which I really appreciate. I am a big fan of the ease with which Glocks can be detail stripped, but the P320 blows it away in this regard. There are no frame pins to contend with, and all the internals can be pulled out as one stainless steel chassis including the frame rails. If you're the type who is really anal about cleaning your gun, then this one is for you. The slide disassembles exactly like a Glock with the exception of the firing pin safety, which is integral to the striker assembly as opposed to being a separate piece.
Another positive is that it accepts P250 mags and holsters, which is what really sold me on the gun. The only real negative to it is the lack of a track record. Being SIG's first foray into the striker market, it will be interesting to see if there are any teething problems like the Gen4 Glocks. But I'm optimistic, and will see how it holds up to higher round counts. Its become my EDC, but I'm definitely not selling my Glock anytime soon.