I loved it, because mainly this game played me very well. I was pretty sure that it would be a Portal in tone and thematics when I saw the beggining. So I took everything that way...
And I loved how at the end, it meant I simply did everything like the game wanted.
spoiler
At first, I was pretty sure that the "voice" in the game was against me, trolled me because I thought it was a GladOS-like. I thought the professor was an incompetent fool that lost control on its invention. I was pretty sure I was against someone that wanted to attack me, to troll me. So I took the challenges and was thinking "here you go look if I'm stupid". But that's what the game wanted, as the idea was it to be the "baby step" to understand we are able to solve things.
And the small speech at the end was really nice, I liked that.
So yeah, for me it was a good surprise. Now I understand that not everybody might feel that way, but I liked it xD