I've used a 92FS for several years in IPSC.
1) The double action initial trigger pull is long and crazy stiff (12+ lb) compared to most other competitors (6-8 lb), so that's a definite negative. However, remember that only the first shot is double action... after that it's single action which is quite nice on the 92, so the trigger pull is an issue only for the first shot. You can make some minor adjustments that slightly reduce the double action trigger pull, but it's still too much.
2) The decocker/safety is on the slide, and I have occasionally dedocked the gun as I racked the slide for the first shot if the stage started with no round in the chamber. I haven't done that in over a year though, so you learn to avoid it.
Those are two fairly significant disadvantages of the gun if you are a serious competitor. Clearly this gun is NOT popular for IPSC. I've only seen a couple of other regular competitors use it.
I'm not wild about the sights, and would have tried to switch them to fiber optic ones, but that's not possible with this gun, as they are milled into the slide (for the 92FS).
Still despite the disadvantages, I've tried other guns, and always went back to the 92FS. It just feels good. People talk about needing "big hands" for it, but I'm a small guy with average sized hands, and never had a problem.
Advantages are rock-steady reliability and effortless accuracy with this gun. There isn't a competition in which I haven't seen someone in my squad have a gun malfunction. Mine never has. Not once.
The Cz Shadow 75 has similar function and ergonomics, without the slide mounted safety and with a much lighter double action trigger pull - it's by far the most popular production IPSC gun. I have one, but it sits in the box unused.
I'm not a top shooter. Far from it. I'm in it for fun and getting out of the house on the weekends during the summer. A serious shooter would not use the 92FS or similar guns competitively, because every little thing counts in IPSC.