I never saw the big advantage of dual wielding. The only difference is you can literally fire both arms at once, otherwise it's just a case of double clicking one trigger to fire, and you can double click quicker than the arm raising/firing animation is anyway.You also had quite a few more options in combat. Dual wielding guns and plasmids opened things up significantly, and then you had extra ammo types, little sister adoption, etc. Stuff like extra turret types and trap rivets/trap spears also allowed for a lot more indirect/predictive combat. Just a whole lot of combat options and ability to combine various abilities.
It still had some of that Bioshock jank but overall it was notably better executed.
Minerva's Den is even better in that area because it gives you access to a wide variety of weapons, plasmids, and tonics relatively early in the game, as well as adds to the enemy variety.