I think it depends on the pan. I use my silicone muffin pans all the time, and I really love them. They're easy to use and the muffins bake really well in them. I only spray the pan if I'm making crustless quiches. The pans are a little unwieldy when full, so I always put them on a cookie sheet or pizza stone.
I've also had moderate success with my loaf pan and 8x8 thin, square pan. The cakes don't brown as well, and the texture of the crust is a little off. I still use them for some stuff, but not everything. I have a bundt cake pan, and I do not use it. The cake is not at all browned, a little flat on the top, and the detail of the pan doesn't show well.