Kind of a mixed bag for me. On the one hand it suffers from what every fan-made portal puzzles suffer: they're either too primitive or too overcomplicated. As a result, the game varies between being too simple and being extremely tedious and clunky. The plot is also messy, it relies too much on repeating the Portal 2 formula, but the pacing is completely off, you spend too long in the first act and rush through the other two, and the ending is... yeah. And in terms of originality, though it may be not too honest to ask a fan made mod to reinvent the game but after Portal Reloaded the experience feels lacking.
On the other hand, the voice acting is really fun and well done, I enjoyed the part of the game with Emilia specifically. I also really enjoyed the locations, especially the surface world. It looks really refreshing for a Portal game. Music also fits the game very well and I could easily mistake it for the original Portal soundtracks. And at the end of a day it's still a game with portals and it's hard to ruin that.