I'm going to be short. The premise, the science, the story overall were great. Enjoyed it to no end. I almost dropped it and didn't pick it back up though, simply because the two main characters did nothing but cry. When one wasn't the other was. It's that simple. This might just be me, but I couldn't bring myself to care about either of them because they were so easily broken. That being said, I will probably watch it again at some point.
On a side note, I'd like to know where they got their math done for time dilation... the numbers didn't seem right.