yes you are. so far, the main changes are just what you saw: things like underwater environments, the use of guns and powers at the same time, and the Big Sister being introduced as the villain.
there are other nuances, but most of what we know so far is covered in the article. honestly, i'm happy if all they do is upgrade the last game. it was good to begin with.
Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete.
Otherwise, please post a new thread in this forum instead.