I was so against this! My oldest went right into his crib from the moment he got home from the hospital and had no issue with it. My youngest however is a different story. He will nap an hour or so in his crib, but prefers his swing. I think he likes that it's upright and snugly and the crib feels too big maybe.
For now I'm trying to do naps in the crib to start the transition, but I'm too tired to not put him in the (unmoving) swing at night. We just started getting longer stretches at night, so I don't want to mess with that!