After weeks of will-she-won't-she redemption plots, this episode was all about showing that Regina is not a good character. She is a morally complex character with some good traits and the potential for a redemption story, but she is not a good person, and despite her need for Henry's love, she typically doesn't realize what true redemption will take or mean.
Welcome to Storybrooke allowed us to see Regina both at her moment of triumph, and so at her most "wicked," and at a moment of defeat, when she has supposedly been down a path of redemption and is mourning her mother. Both Reginas are manipulative, cruel, and fail to understand the nature of human emotion and affection, even as they crave it. In past!Storybrooke, we see her wanting the genuine respect and affection of the people around her, and her desire for a real fresh start, where people might genuinely like her for herself. The episode reveals part of her motivation behind adopting Henry in the first place, and her genuine desire to be loved and be a mother to him, even if she messes up along the way. Yet past!Storybrooke also shows that Regina was a horrible, horrible person. She trapped everyone (including herself!) in a kind of Groundhog Day situation for years and years and years. For more than 28 years, she used his heart as direct and indirect leverage to rape and control Graham. And she is so eager to retain the young boy's affections that she is willing to arrest his father and take away what little family he has left to keep him. She is not, by any stretch of the imagination, a good person. The fact that she evokes any sympathy at all is a tribute to the actress's skill.
Meanwhile, in modern day Storybrooke, Regina plots a spell to make Henry think that he loves her, a spell that requires the use of Snow White's heart. The very fact that she is willing to cast a spell to control her own son's emotions -- a son who she claims to love and wants to protect -- shows that she is still far from redemption, and still doesn't realize what true love actually means. The saddest part of Regina's attitude here is her failure to understand that Henry does love her. Since she's tried to kill many other people in his family and failed him repeatedly when promising to give up magic, it's a very complicated kind of love, but he loves her none-the-less. Yet Regina would rather things be fake and simple, and she is willing to kill and manipulate to achieve it.
I know some viewers have been upset that Rumplestiltskin seems to get off scot free for all the terrible things he does and has done, while Regina is constantly punished and hated by everybody, but I think that, as this episode shows, Regina is neither deserving of complete forgiveness nor considered equal to Rumplestiltskin in terms of evil. Rumplestiltskin is subtle, and although he's morally grey at best, he's never done anything to directly hurt any of our main characters (that they didn't at least agree to as part of a flawed deal). He was behind a lot of the curse, but no-one really knows that. I'm not sure even Regina knows the extent to which he was behind the whole thing. He'll help people when it pleases him, and as such, no one really trusts him, but he hasn't made himself many non-villain enemies either. Regina, meanwhile, has always been focused on vengeance and loves to make a big show about how powerful and spiteful she is. Neither of them is good, but Regina makes it harder for others to ally with her... and unlike Rumplestiltskin, she's unwilling to accept grudging partnerships, temporary deals or shaky, resentment-filled family alliances. She wants nothing short of pure affection, even if she has to do horrible things to achieve it.
Considering the messed up, manipulative relationship she had with her mother, and her desperation for her mother's affection, right up until the end, that's hardly surprising. Regina's story is certainly not without sympathy and the constant hope that she'll learn from the past and eventually get the family she craves. But this sympathy doesn't mean that she's a good person, or that redemption will be coming any time soon.