It takes practice, just like any other technique.
Exactly. I'm a finger-style player, but there are definitely some benefits to playing with a pick. I've used a pick instead of my fingers while recording some tracks with alot of chords, and fast Black Flag-type picking (I am faster with my fingers, but to get a really even sound I'll use a pick or one finger.)
Just keep practicing, it can't hurt to add another technique to your arsenal.

Even though I don't use a pick for many songs, I've now built up my hand and wrist strength to the point where I can play uptempo tunes such as "Slither" by Velvet Revolver and "Mudshovel" by Staind. I try to play "Slither" with all downstrokes, sounds better that way to my ears.