Honestly one of the greatest game experiences I have ever had.
The graphics and story are both amazing, a huge highlight is also the amazing soundtrack that gives this nostalgia-ery otherworldly feeling to it. Especially when it ramps up during flight/freefall. The voice acting is amazing and Wheatley and GLaDOS have loads of character and personality unlike GLaDOS from the first game.
The best bit to me is old aperture, you get this amazing feeling going back in time and seeing the barely touched past and seeing remnants of the 50's-80's of aperture, being all the way down there and hearing the whole facility crack and creak around you is so breathtaking, and you just want to know how big this place is, the sense of scale and wonder about the thousands of untouched corridors and secrets in this game is amazing, still looks good in 2020. 1 was an idea, 2 was the game.
10/10 must play, I don't even like puzzle games :)