It's not unforgettable. It's rather very forgettable.
But don't call this game a masterpiece because it is not masterpiece. It is solid, good for killing time and at least fun first person shooter. Interactivity with the environment is as minimal as possible. You can't talk with any of the many similar looking NPC's. Not to mention arcade-ish like collecting method (I will take some coffee and candy bar from this trash bin, but just look at that voice acting and story level...bah). "It's the way we like to play games", said someone from the developing team. Ok, but don't mind then if your game is at same level as if it came out in 2007. Because in 2008, Fallout 3 came out. After playing Fallout 3, Infinite looks kind a...meh. I know F3 is RPG at its core, but it is first person experience nonetheless. One really big issue with this game is saving system. If someone could tell me what happened between first Bioshock and its manual saving system and Infinite's checkpoint system? Same problem has Hitman Absolution. You just can't put an autosave system as an only saving option in a game which is based (partially, doesn't matter...) on exploration. Let's take for instance, the beginning of The Battleship Bay level which you need time to get use to, to get all the collectables, to explore the environment, and if you play it for 10 minutes and suddenly you must to abandon game for some reason, you will have to start over next time. Bioshock 1 didn't have that much more space to explore than Infinite, but you could save anytime. Lately, developers are so afraid of the manual saving system as it is some kind of leprosy. Why? To keep us glued at the screen? More likely to repel.
Bottom line: without creating spoilers in this review, just to say that
Bioshock Infinite is built much more than it should have been at the glorious foundations of the original Bioshock (lacking manual saving option). It would be better if the setting and story had a bit less metaphysics and level of enlightenment to the players, but more immersiveness and gameplay.