They are pretty trouble-free. The California Highway Patrol adopted them as their issue gun in about 1990. They shoot monthly so their guns get plenty of wear. CHP liked them well enough that they bought new ones recently to replace their originals. That is an endorsement of the durability and reliability of the gun.
My department adopted it as their first issue semiauto in 1991. We had no troubles at all. Some folks disliked them because they were heavier than, say, a Glock or Sig, but the weight makes the S&W easier to shoot well.
I bought mine in August, 1990, when S&W began shipping them to dealers. While I haven't got a real high round count in it (perhaps 1,500 rounds total), it hasn't ever had a stoppage.