I don't really like Nell-as-Hetty either. I think it's because the actress is so young looking, and the character has come off as having limited field experience (whereas Hetty is ... well, Hetty lol). It seems like a job that would require a lot more life experience and understanding/bonding of the team. Nell's reaction at wanting the Kensi pic off the screen was totally something I'd expect from her ... but not from the operations manager. Hetty had to keep it under wraps until the mission was done, even if it meant looking at upsetting stuff, and I just don't see Nell being there yet.