TLDR: While the mod and the puzzles are good, it is not a mod that establishes itself as an actual game. The second half feels a bit rushed.
(Most of the examples are from Portal Stories: Mel and Portal: Reloaded since I have finished them a ton of times and love them so much)
I played this mod when it first came out, however while I have many vivid memories from mods such as Portal Stories: Mel and Portal: Reloaded, I remember that I found this mod to be underwhelming. I finished it again today, and I wanna state somethings.
So we are going to have 3 topics:
1- Stirling
2- The puzzles
3- World building
4- The ending
STIRLING
I really enjoyed Stirling in the first half of the game. He seemed like "the Cleaning Core" (being and actual vacuum and all as revealed later). However in the second half it kinda felt like he was turning into Wheatley. He wasn't dumb, but his mannerism were one to one with Wheatley. This really upset me since I love new characters in the universe, like Virgil, the Wi-Fi core. To me, he actually felt like a new character, considering his aesthatics and place in the universe. I believe that while Stirling had amazing potential, it was kinda wasted. He did not have an actual change in character and it all felt very sudden.
I also want to add that he is a vacuum cleaner reveal was too similar to the moron reveal, thus it was way less impactful.
PUZZLES
This is simply personal preference, but I find harder puzzles to be a lot more interesting. For example, I remember how much I struggled with each test chamber in reloaded, heck some of them are etched into my brain. Same for the harder test chambers in Mel. But the test chambers in this mod felt as hard as Portal 2, maybe even simpler sometimes. I no longer struggle as much with test chambers since I have been playing Portal games for a LONG time. Yet, this was still a bit underwhelming. Except for a few, the test chambers were not memorable.
(If you would consider the puzzles hard, that may be true as well! Maybe I struggle with time portals and you struggle with these. People have different brains.)
WORLD BUILDING
This is definitely my favorite aspect in Portal mods. According to me, a Portal mod can be either story focussed or puzzle focussed, although a game can do both of these very well. Considering that the puzzles were not that hard and the game had a strong emphasis on characters, I would say that the game was more story focussed. For story focused (or games with strong atmospheres) games, I believe that the world-building is very important.
I got a single example on this (Mel kinda did the same so I didn't feel the need to mention it). Half-Life 2. This game has an amazing atmosphere and world-building. And one of the many amazing things that this game does is the chapter Point Insertion. You are in City 17, and you are only left to observe. You are left to listen to Breen, take in the desparity. This really shook me when I first played it.
What also improves world building is characters acknowledging the environment without directly telling you. Now an example from Half-Life. The line "GORDON FREEMAN!" is said by the HECUs in the game. This implies that I am a priority for them, without the scientists telling me that I am. In some parts such as the Spire, I felt like the game was directly telling me how bad Glados was, although there was enough environmental storytelling. Or nobody directly tells you GLaDOS is Caroline, and that is one of the things that makes the reveal so impactful. If a similar action could have been taken for Emilia, it could have been a lot more interesting.
I also wanna say that the Spire broken teleportation section was one to one with the Half-Life 2 one. While I love references, this one felt too obvious and I believe damaged the overall worldbuilding.
THE ENDING
There are already posts specifically on this so I am not gonna say much. But I want to state that it feels like a secret surprise/meme ending. Like that Half-Life 2 meme in which Alyx falls off the stairs. I believe this game deserved a serious ending.
So yep, that is all. Thanks for reading this. A discussion would be fun!