It did look very similar to GTA V, but it’s also worth noting that pretty much all of the footage was from very early production. It’s likely that they were using less detailed character/world models for testing purposes. I imagine the game will look pretty damn good and modern once the proper lighting and textures are applied.
Ultimately I don’t remember anything incredibly interesting from the videos I saw outside of a couple of story beats revolving around the new main characters. It seemed like most of the videos were pretty much testing certain console and systems at non-specified points in game.