I play terran a lot and I use nukes all the time. Especially in 2v2. I'm only silver league in 1v1, but I've never had someone use a nuke on me once, except for friends. In a few hundred games. It's alot of fun, and its definitely pretty effective once you learn how to micro the ghosts. I like to get 2 ghosts, 2 nukes, and used it to obliterate a big gateway or barracks wall, then rush into the base with the rest of my force. Sometimes does blow up in my face though heh.