I played it hard and apart from a few frustrating moments, I thought it provided a fair challenge. It may have helped that I picked up some good gear (melee kills restore health, melee attacks set fire to enemy 70% of time, getting hit electrocutes enemies 50%(?) of times, and double shield recharge) early on and, by the time I got Charge with the explosion and shield restoration upgrades, the Lady Comstock fight was not too bad. Surprisingly for me I didn't die once on the final battle.
My only complaint for hard difficulty is that some of the higher tier enemies like the rocketeer and volley gunner became bullet sponges and took more time than was fun to take down.
As for 1999 mode, the poor checkpointing in the game has turned me off from trying it. The checkpoints are to infrequent and the possibility of having to replay large sections doesn't appeal to me.
Why do all the Dewitt's converge at the baptism? If we have multiple dimensions, with different constants and variables, then there's a Dewitt that doesn't get born, a Dewitt that doesn't join the army, a Dewitt that is in the army but not at Wounded Knee, a Dewitt that is in the army but not at the Boxer Rebellion, etc.
The story is fine; it's certainly a mind fuck, and I kept screaming "WHAT!?" at my TV when they warped to Rapture, but it seems a mind fuck for mind fuck's sake. Every plot hole or loose end can be swatted away with "Oh, multiple dimensions." Like Bioshock, the star of Bioshock: Infinite is Columbia. It's a breathtaking tapestry of technology, religion, racism, and the oppression and subsequent violence caused by their compression into a single, floating city, cut off from the rest of the world.
This was my feeling on the ending, too. I enjoyed how they showed the ending with Rapture and then seeing the infinite lighthouses but once you introduce a multiverse then your story becomes a bit silly.
What I enjoyed most was how they subverted the damsel in distress thing because I'd argue that it's Elizabeth who ultimately saves Booker from himself. By eliminating all the worlds where Booker either becomes Comstock or gives up Anna, Elizabeth stops him from becoming a crazy evil 'prophet' or making a decision he regrets so badly that he has to scar himself. The post-credits sequence shows Booker with baby Anna, showing that there is a world where the two are together. Obviously, by introducing a multi-verse, there's a possibility of there being infinite world where Booker still gives up his child to someone else or doesn't have a child at all, but its best not to think about those.
The parts with skyrails are fantastic. I never played much BioShock 1 or 2 so the shooting/magic power combo is still pretty fresh for me and I'm enjoying the variety it brings. At where I am currently in the game Booker is basically a Vanguard out of Mass Effect, I'm using charge to bash into enemies from across the other side of the level and then shotgunning them in the face.
Also, based on advice from people on Twitter, I started the game on hard and I feel its provided the right amount of challenge, so far.
Was waiting for reviews to make sure the game wasn't completely broken or anything but I was always going to get it even if it got middling scores. Great to see that it's getting such praise and can't wait to play it tomorrow. Also happy for Ken Levine, that dude has been doing like a billion interviews and press over the last few weeks and it's cool that he can finally enjoy people playing his game (along with the rest of the people at Irrational).