Once I started playing, I finished Act 1 in one play session. The story was really enjoyable, although in all honesty I enjoyed Vella's story more than Shay's, because her interactions and environments felt more alive compared to the sterile spaceship. On the other side, the humor in Shay's story was quite good and made me laugh multiple times. The puzzles weren't overly difficult, and that's a good thing. It felt balanced.
Lastly, I finally understand Tim's reasoning for not wanting to split up the game in two parts, because Act 1 on its own seems quite short. However, I am sure that Act 2 will not disappoint given the quality of Act 1.
Good job Double Fine!