Non/Never-smoker here. I started taking Nicotine lozenges when I first heard about this a while back to self-medicate ADD/Depression (too poor to afford insurance, will have it in 60 days and this will stop). It works incredibly quickly, and incredibly well. I take it as needed, I've gone over a week without using it and it's not remotely an issue. Zero rebound depression. Definitely helps focus.

All the anecdotes I've seen of being addicted to nicotine gum or patches have been of former smokers who were using them to try to quit. That's not necessarily nicotine being addictive so much as their pre-existing tobacco addiction latching onto a replacement.