With regard to your question, the Gear S2 is the best smartwatch on the market, but it is not an Android smartwatch because it runs Tizen, Samsung's own operating system, not Android Wear (Google's Android platform for smartwatches). The Gear S2, however, can pair with all Android smartphones running Android 4.4 KitKat or higher, so it essentially does what an Android smartwatch will do and more.
It is the best smartwatch for a number of reasons, but one is battery life. If the Gear S2 were an Android smartwatch, battery life would be limited to 18-36 hours. Fortunately, the Gear S2 runs Tizen and has anywhere from 2-4 days of battery life depending on usage. I generally get 3-4 days of battery life out of the Gear S (which is Samsung's 2014 smartwatch that runs Tizen), but some will get 2 days max because of moderate use.
Yes, though, the Gear S2 is the best smartwatch out there. It has wireless charging for your smartwatch so that you don't have to fidget with charging cradles and wires, allows for interchangeable wrist straps, and has a rotating bezel (which is, by far, the sexiest thing put on a smartwatch). Since Samsung owns Tizen and powers its own Gear S2 with it, you will get something fresh and different from what the majority of Android Wear will offer you.
I'm maybe the wrong person to ask because I do happen to agree with the reviewer. I don't know if he or she explained it in the article you read, but the Gear S2 is a Tizen smartwatch that is compatible with Android smartphones -- in the same way that Pebble is compatible with Android and iOS but runs on neither. Let me know if you need additional clarification.
As wonderful as it is, I suggest you go to your local store and try it out for yourself. I highly suggest the Gear S2 3G model. Having the Gear S 3G model for a year now, I would never go back to a Bluetooth-only device. But yes, it is the best smartwatch money can buy, and it has not only good looks but battery life and functionality to match! Happy shopping