Well I've almost completed it. I think I'm up to the last fight. I really wanted to complete it last night but it got to 1am and had work in less than 6 hours...
As a big big fan of the first two games I started the game excited. The first 5 minutes are beautiful, the set looks fantastic and really is great to see a developer going that extra mile with little touches littered everywhere.
Then I start to get a little disappointed, like Scort said - hardly any details to who I am, why I'm here and the plasmids are just presented to me without real explanation. There is a real lack of story for the first 30 minutes, just nothings really explained and I don't think the VoxRecorders add anything like they did in Rapture...
...However, a little further in - everything starts to click. The combat feels good. The levels feel much bigger and you get a sense of exploration like you did in the first Bioshock, so much so you find yourself constantly straying from the intended path. I'm playing on hard and it feels challenging, using the plasmids to effect and different weapons on different enemies. After you meet Elizabeth the story picks up and starts to make sense. As the game goes on you build up a relationship with your character and Elizabeth and have that thirst for pushing forward to see how the story and the characters develop.
Some of the places in Bioshock are a pleasure to explore, The Hall of Heroes being one of the most notable - Reminds me of Fort Frolic from the first.
Playing Infinite, I felt like that we need re-visit Rapture and base the story around just before 1959 so you get a idea of what rapture was really like before just like they've done with here.
Like I said, I've not fully completed it yet but already I'm looking forward to my second run through to mop up any achievements. I've already purchased the Season Pass. A fantastic game full drenched in atmosphere and style.