Marta was clearly a great choice -- just look at our results since she took over.
Why Marta? She knows what she's doing and had a better relationship with the coaches than Bela. I'm pretty sure that the coaches at the time voted on that, but Dunno can correct me if that's wrong.
She stays because it's her passion and she's doing a great job if results are what you care about (I would think that's how USAG would evaluate things), but yes -- she will retire. Valeri is set to take that role over as far as I know and that transition/"passing of the reigns" has been taking place for a while now. Not sure when or if a planned retirement date is known, likely after 2016.
As far as Marta being nice or not nice, I'm sure that is a matter of opinion based on based on individual experiences with her, but anytime someone is telling you something you don't like, it's going to rub you the wrong way. She's not in the business of being nice -- she's in the business of putting the best athletes on the floor to represent the USA. And American's like to win. You know the old saying "Nice guys finish last"....it has some truth to it. I'm sure some of the disconnect may be cultural, but I just get the sense that she is very no nonsense, she knows what she's looking for and she knows when she sees it. And she knows when she doesn't. She's got a great track record, so it's hard to argue with that. But it is hard not to take it personally if you're rejected, but it is what it is.