I’ve used mine to prime several thousand pieces of brass, including a couple thousand with the Federal primers that Lee strongly recommends not using with the tool. I could prime on the press, obviously, but I don’t like handling metal tubes full of impact-sensitive high-explosive. I’d rather size/deprime and flare, prime with the Lee tool while watching TV, and then load.
I have not had any problems with breakage so far, knock on wood, though I could imagine that the pivot in the handle might break if there was a casting flaw near that area. I also have some doubts about the latch that holds the plastic primer tray lid on.
The cam (for lack of a better term) did develop notches from priming several thousand pieces. I ground it smooth, and it happened again. I bought another one, and case hardened the "cam" with Casenit, and it seems to be holding up with no sign of wear. Not a big deal considering the tool costs less that $20, and I had lost a spring anyway.
That’s pretty much all there is to say, it’s a simple and affordable tool, and it works.