Only been through the drive thru, but the window servers always have been very courteous and attentive. There was one time towards the end of the night where the girl clearly wanted me out of her way as soon as possible so she could socialize, talking about her coworker who was about to "throw up", but I feel it's wrong to judge all my experiences based off one less than satisfying trip!
I would be prepared to ask for extra toppings in the blizzard, since they tend to skimp.