Brand = HOT, but...
DUMB as a box of rocks
First things first: let's state the obvious. She's way way too hot to be a smart scientist. She probably sucked his way on the ladder by blowing the entire NASA department, and that includes her father.
Then she probably even gave several blow jobs to Cooper, otherwise he wouldn't have accepted going on a mission with such a dumb broad.
Now let's talk about her intelligence:
She's like "oh yeah let's go to Miller's planet (close to a black hole), and then she messes up looking for the radio receiver. Then she's like "oh well, I blew it again, let's go to Edmund's planet", because well... she obviously missed his HUGE COCK.
Then at Dr Mann, she's hitting on Mann all over the place and when Mann takes over the ship she's like "oh, is he marooning us?" and Cooper is like "NOOO! REALLY? I thought he was going to get us Lakers tickets!!!"
Then finally when TRAS is like "see you on the other side Coop", and Cooper is like "see you slick"... Brand's face is like she just stares there looking at nothing, wondering whether if she left the stove on or who killed JR.
Great movie seriously, but Brand really needed a sex scene to make up for her stupidity.