I certainly liked what they seemed to be trying to do with Diana, if that counts?
I invited her onto my ship with the expectation that she was going to unlock a sort of "hearts and minds" subplot which I would have found really interesting. By which I meant I expected there to be at least one point in the game where something hugely important happened and a massive fight was going to erupt about the tensions between sensitive information, the public's right to know, influence on morale and whether we were protecting people by NOT telling them everything etc etc. Especially with the Shadow Broker on board. I thought it could have been really interesting to examine the tensions between what information we COULD release and what information we SHOULD release.
That didn't happen though, so Diana ended up being just kind of...there, and unfortunately for her she was the least interesting person on board the Normandy. The most interesting thing she had to offer was probably her conversations with Traynor. She's not horrible as a character IMO, although I did resent the fact that, out of game, she's probably the reason I had to watch Emily Wong get killed off on twitter.