I mean, it's Bioshock. Saying Bioshock is good is like saying water is wet. It's a streamlined ImmSim experience brought to the modern age, with an immersive world, an intriguing story, extremely good voice acting and dialog, and high replay value. This game has aged like a fine wine due to its presentation and art style as well. It's action-packed without being overly flashy. The narrative is dramatic without being ham-fisted. The gameplay is fun and heavily rpg-esque without being too janky.
That being said, here are the flaws because I love to complain. The last few hours of the game are a serious miss. The escort mission with the little sister and the hilariously high difficulty spike kind of sour the experience, and the final boss is very lackluster.
Overall though, no game is perfect but this one is still a masterpiece. Best in the series, even. Go play it now.