I'm going to have to agree with Miranda. She isn't just whiny and spoilt, she has had a difficult childhood with an abusive father, and processing your achievements, knowing that everything you did was because of the talents genetically engineered into her takes time.

She's not an angel, and she does have streaks of spoilt, but she is a complex character, who develops as the game continues. By ME3, she's worked through most of them (especially if you're a paragon).

That's why I find Paragon in ME2 the best, as you basically play combat therapist to most of your crew.