The project was always - CLEARLY - meant as a spiritual successor to System Shock 2. You can watch some of the earlier Gamespot interviews - and you'll find that the original concepts were much closer to System Shock 2. But, as time went on - and the budget bloated - they had to dumb it down and make it appeal to a wider audience, with familiar shooter mechanics and forgiving gameplay.
That's not spelled out, obviously, as that would be very bad PR. But it doesn't take much reading between the lines to see how Bioshock happened.
So yes, Bioshock is a shooter more than it is anything else. I don't particularly care for shooters.
If you prefer straight-up shooting to something more cerebral or with a slower pace like System Shock 2 - then it makes sense that you would prefer Bioshock.
To each his own, as they say.
Note that I'm not saying you have to be dumb to play Bioshock - as that would be a stupid thing to say. All I'm saying is that the gameplay mechanics and the overall design is a dumbed down = simplified and more accessible version of System Shock 2. It's not "just a shooter" - as it's incredibly obvious where it gets its non-shooter elements from.
Levine failed to learn from Looking Glass. Well, he didn't - because he made the game a huge success, and LG went down because they were too innovative and their games weren't accessible enough as a result.
After I got over the massive disappointment of Bioshock being basically just an atmospheric shooter with a handful of half-assed RPG elements - I rather enjoyed it. Well, right until the "twist".