The New Smartsheet Navigation Experience is GREAT!
The #1 feature I'm excited about is Browser Tabs and Direct Links. Being able to copy the URL straight from the browser. I spent a LOT of time as a champion and mentor explaining how to get the URL to share a specific sheet. I really believe this will enhance the new user experience tremendously!
Thank you, Smartsheet Team!

2018-12-20-Update: I have to admit, I am only working in single, unrelated sheets right now. I can see the new interface being frustrating when working in multi-sheet solutions like I used to.