Dreamfall is a worthy sequel of the longest journey.
The previous point and click interface has been change to full 3-D movements and interactions (no jumping). The fighting features added are overly simplistic and are one of the worst features of the game (but it's easily ignorable). The environment looks much better than before and is wonderful to look at, albeit a bit empty at times.
The new protagonist Zoe, is just a memorable as April. Previous side characters make re appearances which is always good. The story has a lot of plot holes by the end of the game, creating more questions than answers. This was done because it was part of a 2 game story, the second game which is still in production and probably won't come out in the near future leaving a major cliffhanger.
The sound falls short of the standards set by the longest journey, though it's still a joy to listen to. The voice acting are still some of the best I've seen in any games. The game is kind of short compared to the longest journey and the puzzles tuned down a lot (for us stupid people). This can be a good thing or a bad thing depending on how you look at it. Good because it means less hindrance as you enjoy the story, bad because it reduces interactivity with the environment.
Overall, it's a worth sequel to look into. It's worth it's value and is a way to spend your weekend(s).