Extremely smooth. Got to my Sprint store around 7:15am. There were about 10 people in line. Waited in my car for about 5-10 mins watching the line. After about 5 more people got in line, I got out and went in to the Panera Bread next door. Got a chocolate croissant and a water, (should've gotten a milk) and stood in line. Sprint store reps started coming outside at around 7:45 with fact sheets about the Evo and a sheet of paper to fill out the names of everyone in line so nobody got skipped once we were in the store. They opened the doors promptly at 8am and had a table with dunkin' donuts refreshments, (I regretted paying $5 for a croissant and a water at this point). They immediately started setting up the first 6 people off the queue and the rest of us either walked around the store checking out the display Evo's and picking up accessories, or took a seat and read the fact sheets. My name was called around 8:25. The rep was helpful and efficient, getting me set up and out of the door in 15 minutes.
Pre-Order what? No need. Walk-In; An overall great experience.