I'm writing about what I hated first, so feel free to skip to the next paragraph.
First the negative: This episode was boring at first imo, but I feel it got interesting once Angela's sister was trying to be injected with that needle, then all craziness broke loose. It seemed as though adult Alice was sort of a psychopath to me, after those events years ago. I personally thought the storyline was too random to be taken seriously. I would've enjoyed it better if Alice didn't survive, and Angela was just remembering the past, but they had to give a purpose for it, this being that Alice was still alive. Positive: I really enjoyed the scene when Alice caused the storm and Mohinder tried to calm her down, and she thought of him as Chandra. That was a nice touch. The conclusion of this episode was also epic, Nathan seeing himself on TV, even though it was Sylar. That was epic. Plus Angela got more depth to her character from this episode. PS Deveaux using his powers to dance with a white girl during segregation was genious.
Conclusion: This was a necessary episode. It had character development, and it introduced a potential villian to the series. I'm glad for it, but I can't wait for next weeks episode.