I was actually not too happy about my overall experience here.
We went last Saturday at around 4pm. The line was 30 minutes, in the shade, but still quite long for only one doughnut. We got up to the counter and were helped by someone who was clearly a manager (was wearing fancy, button-down clothes, not the voodoo doughnut outfit). We asked for a Portland Cream and we were given a very terse "we are out" answer. No apologies, or recommendations for other doughnuts. He just stared at us annoyingly while we tried to decide on another doughnut.
We got the Captain My Captain, which was pretty good, but it was hard to enjoy after receiving that level of customer service which caused us to not return for the rest of our trip.
Anyways, just wanted to put this out here to keep expectations level for this place and recommend that you get there earlier if you want some of the more popular doughnuts.