I recently finished playing BioShock.
Overall, it is an excellent game, probably the best game of the year so far. That said, I keep thinking back to my previous gaming obsession, The Elder Scrolls IV: Oblivion, and somehow it was never quite as captivating. I logged over 100 hours in Oblivion and mostly stopped playing in order to get some sort of a life back (World of Warcraft players, I salute and pity you). BioShock clocked in at probably one fifth of that time, but somehow there was never that compulsion to play, that planning your life around figuring when you can get back to the game.
What's good about BioShock? The graphics are amazing, certainly. The Big Daddy is simply an awesome character, perhaps one of the most memorable characters I have seen in years. The setting is very cool, an underwater city in 1920s art deco style. The sense that Something Very Bad has happened is ever-present - there is scarcely any part of the city that is not falling apart in some way, leaks and rubble everywhere. Thinking back on the sterile environments of most games of even a few years ago really makes an impression as to how far games have come even recently.
Still, I just don't feel as excited about the game as I think I should. Maybe it's because the story gets a little derailed after the main plot twist (and the story was a little confusing to begin with). Maybe it's that the final boss battle is such a departure from the rest of the game. (Really, the ending of the game is a bit of a letdown.) Maybe it's because the game takes control away from the player at some key moments, most notably at the end. Really, the places where control is taken away are exactly the points in the game where giving player a choice would have made the game great. (Note to self: After the final big boss battle, do not take control away from the player and end the game immediately.)
Maybe it's because, despite one attempt at allowing the player to make a moral choice, the game forces you to do some rather questionable things in order to advance. That linearity to the game is really the biggest weakness. At the end of each level, the game's transportation system will allow you to travel to any of the previous environments, but there doesn't seem to be any compelling reason to do so.
All of the ingredients are there to have an open ended game with multiple solutions to each problem (the easy, evil road, or the hard, good road) but they were never executed on. I really have to suspect that that is the game that was originally designed, but could not be achieved for reasons of money or time. Being a game developer I have an immense amount of sympathy and understand as to why those things may not have panned out as expected. Certainly the pressure to get the game out the door, especially one as good as this, would be immense. Maybe I'm just disappointed that what could have been an all-time classic (as I would expect Oblivion to be considered) will go down as one of many games-of-the-year that are all too quickly forgotten.
Buy it, enjoy it, just don't expect it to change your life.
See also: Zero Punctuation Review of BioShock