To be clear, SW is also NURBS, it just happens to retain the history of those functions (macros). So the way things are built will feel very familiar. In other words, it's not like moving to poly modeling, which can be an entirely different workflow.
The stuff that takes getting used to, for me:
1. No dialogs or wizards; all messages and prompts appear in the text box up top
2. It is very easy to accidentally be imprecise. Add this to the fact that the onscreen visuals are always approximated, so something that looks to be in the right spot might actually be a little off, unless you make sure that you're snapping correctly.
3. Whereas SW will yell at you for every little invalid thing you do, Rhino will just let you live with your shitty geometry. This is really good for quick modeling, but terrible for diagnosing failures.
My mind is in more of a Photoshop mentality when I'm using Rhino. Meaning: liberal use of layers, duplicate+hide any object that may need its changes reverted. To me it's a much more sculptural process; less step-by-step than SW.