Better than the first game in ever way.
You play as a Big Daddy which is already cooler than playing as just some dude.
The story and characters are more interesting. The lore and origins of Rapture are much better explained.
The machinegun and shotgun were still my go-to weapons, but I enjoyed the others as well. You can now use Plasmids and guns at the same time which makes the combat much better.
Big Daddies are more difficult and fun to fight here than Bioshock 1 and Big Sisters are really cool too.
You can walk around in the ocean outside Rapture too, which is neat.