After playing the game through to completion, I can tell you right now that this is not worth your time. The paint gun makes puzzles FAR too easy, especially when they begin recycling levels from portal 2 itself. The voice actor I'm sure tried his best, but it was not good, I'm sorry, making the personality core sound like a shoddily modded dimwit. Also, the core is never actually used as a core. It could have remained unrevealed for the entire game and it would have felt no different.
Gameplaywise, I spent a considerable amount of time shouting at the gun's physics. Some levels require you to move quickly spraying gel in front of you, but the physics-based gel BARELY MOVES FASTER THAN YOU DO - as a result, you have to KNOW something is there and spray it long before reaching it or the gel won't register as it lands at the same time you hit. Fail to know, and the level - there's one specific level I'm griping about - becomes a chore where you have to memorize every single thing and prepare for it long in advance - before you can even SEE it.
Other than that, the gel idea just felt too lazy. The whole game felt too lazy. I have seen more effort put into many workshop maps on portal 2 itself.
Would I complain normally? No. But this mod actually has the gall to CHARGE MONEY. And when so many mods are out there that are FREE for Half Life 2, Portal, so on so forth - hell, the entire GAME of team fortress 2 being free, this mod is NOT worth any money, period. It is unpolished, buggy, feels VERY lazy the entire way through, and has a terrible ending that leaves you thinking "That's it?". It tries many times to crack jokes also in relation to the Cave Johnson style in Portal 2, but the bad voice actor coupled with terrible, very obviously poorly scripted dialogue makes it simply an annoyance.
Now, on the other hand, the music is fantastic. A++. Someone give the composers an award. It's one of the only reasons the mod remains playable with all it's issues, lame recycled art style, lame concept, bad dialogue, bad voice actor, bad physics reliance, etc. The music was beyond fantastic and I hope they release it for purchase or download or something.
I was also very impressed with the audio system that utilized speakers to send out music, which rather than simply having some strange background music playing in a game gave a bit more of a sense of immersion, as you know the core is playing the music and that it was intended as part of the level, while also giving the developers a chance to toy with the music using dialogue from the core too.
The only other thing that impressed me was a single plot twist, but personally, I do not find it enough to justify paying for this when so many games that are entirely free can out-match it on all levels.
All in all? DO NOT SPEND MONEY ON THIS. If they ever make it free, which they won't because they're probably getting a ton of cash right about now and don't frankly care, then it is worth it as an above-average mod. As a paid mod, which I can consider a full game? What else can I get for this price...
Well, you wait for a steam sale and literally every single game is as much or less than this mod...
The entirety of the tomb raider franchise is available, with each game costing the same or barely more than this mod...
Civilization 3 is cheaper, along with Binding of Issac, Plants vs Zombies, Half Life: Blue Shift...POSTAL...Half Life Opposing Force...Any of the sonic the hedgehog games (classic ones, which are great)... I'm just running through the list of games under $5 right now and finding ones I know are good. This mod at full price is $7.
DO. NOT. BUY. IT. As mentioned, if it's FREE, it's worth your time. If it's PAID, spend your money elsewhere. Do not support this new "money for mods" deal, because you know others will follow suit if this takes off.