We found a nice review about The Expanse 3×02 and this is the part about Anna and Elizabeth:
We spend most of our time on Earth seeing things through Anna’s eyes, and she’s an immediate, and welcome, addition to the cast. Part of this is because it’s a relief to have someone who’s not a corrupt asshole facing off against Errinwright (not that Esteban is necessarily as much of a monster as Errinwright is, but he’s compromised at the very least); the first time we see Anna, she’s intervening in a near riot and insisting that protester get his broken arm treated. It’s always possible that her principles will serve as an obstacle later on, but for now, it’s just good to see someone who actually believes in being a decent, caring human being.
The other reason Anna is so welcome is Elizabeth Mitchell. Mitchell’s obvious warmth and intelligence helped make her turn as Juliet so indelible on Lost—that she can be idealistic but never come across as foolish or predictable is a great gift, and she fits right in with the cast as it currently stands.
The author of this review also wrote a nice message on twitter:
Had completely forgotten Elizabeth Mitchell was on this season of The Expanse, and am _very_ happy to see her.
We just want to say that the fans of the show are giving a nice welcome and a very positive reaction to the introduction of Anna and especially to Elizabeth, which makes us really happy, because this woman deserves all the love the world is capable to give her. <3