“Mission accomplished,” writes Piper Jaffray’s Gene Munster in a report to clients issued early Friday, the day after Apple’s (AAPL) biggest product launch ever. “Apple has in three years built brand loyalty in the phone market that compels users to upgrade to the latest version and wait in line for one to six hours to pick up their iPhone.”

“While we think Apple will sell between 1.0 million to 1.5 million iPhones in the first three days (including preorders),” he writes, “the actual number is largely irrelevant. Apple is tapping into the global consumer spending sweet spot, mobile, and as a result iPhone numbers are going higher in the coming years.”

We suspect Munster is hedging his bets with that 1-million-to-1.5 million estimate, given his shaky track record predicting launch day sales (see here and here and here). [Update: Four hours later, Oppenheimer’s Yair Reiner estimated that Apple sold 1.5 million iPhone 4s the first day alone. See here.]

Much more useful are the results of the survey he and his team conducted in the Apple Store mayhem Thursday. They managed to interview 608 iPhone 4 buyers in San Francisco, Minneapolis and New York, asking the same questions they’ve asked at every iPhone launch for the past three years. Their key findings:

• 77% of the iPhone 4 buyers they spoke to were upgrading from a previous version. That’s up from 56% in 2009 and 38% in 2008. Last week, Morgan Stanley’s Katy Huberty predicted that the upgrade rate would be roughly 50%. See here.
• 16% of buyers were switching carriers to AT&T (T), down from 28% last year
• 54% purchased the higher-capacity 32GB model, up from 43% last year
• 28% already owned an iPad
• Of the 72% that did not own an iPad, 39% indicated that they would likely purchase one in the next 12 months

We note that Research in Motion (RIMM) was the biggest loser Thursday, as 6% of the buyers surveyed were switching from a BlackBerry. Next in line: Google’s (GOOG) Android, with 3%, and Nokia (NOK) with 2%.

Below: The full survey results.

See also:

• First day sales: 1.5 million iPhone 4s?
• What’s driving iPhone 4 sales
• What the iPhone means to Apple

[Follow Philip Elmer-DeWitt on Twitter @philiped]