I've used them from time to time, but not my usual choice. But my decision to purchase CCI's rather than Win. isn't because of a problem with reliability, as I've yet to ever experience a single misfire with any primer in more tha 30 yrs. of reloading.
My sole reason for using CCI's over any other primer is simply due to how they feel when I seat them. To elaborate, when I seat a CCI I can feel the cup making contact with the bottom of the pocket, thus assuring I get a good pre loaded of the anvil. With Win. primers, they don't have that tapered cup like the CCI. Neither bad nor good, it just makes seating them to the ideal depth more cumbersome, IMO.
So if I needed primers and couldn't find CCI's on the shelf, which has happened, I don't hesitate to use Winchester's.
One other property of Winchester primers is they seem to be a bit hotter than CCI's, which isn't necessarily a bad thing when working with ball powders and those which can be hard to light or finicky in cold weather too. One example of this, is when I'm loading with 296 I've had terrible results with standard CCI's rather than magnum's. But when I tried the same loads using Standard Winchester's the results were much better, nearly that of a magnum CCI. So the bottom line is, if you need a primer, Winchesters will get the job done, and just as well as any other brand.
GS