An interesting challenge
I'll admit to being sceptical when I saw the numerous allusions to Portal, for as good as that series is, the vast majority of games that pay tribute to it do so in a poor manner.
That said, I found this to be an intriguing puzzle game with enough challenge to keep me playing until I finished it. Though the music looped I found that it didn't become annoying, and the voice acting was very well executed - I did find the AI character to be just a little too similar to GLaDOS, though. I will, however, praise your restraint in not parroting 'The Cake is a Lie' (or a facsimile) in the thoroughly annoying fashion that the internet community has on the whole adopted.
Another small complaint I had was the limitation to one use of each of your duplication powers per level, rendering some levels irritating, and I felt needlessly so; in many cases messing up the use of the power would have required a restart of the level anyway, but on the few occasions it did not, I found it a chore to have to redo sections of it just because of a slight mismovement, especially with thesomewhat unstable nature of the characters on the corners of platforms.
I would also have commented negatively on the difficulty curve, as the second to last level seemed to require such unutterably precise execution as to be ludicrous - however, I double checked my solution against the walkthrough after beating the game, and found I had made things far more difficult for myself than the designer intended by finding a slightly different solution!
I'd be interested to see an improved sequel.