Those sections were cool, but every other part of the combat was fairly boring to me and more of a means to an end for moving from place to place. I love Bioshock, and I really enjoyed Infinite, but probably not because of the combat. It felt like a step down from the previous game to me. After sitting on it for a few months, I think I really just liked the setting and the characters. The story was good, but I had to read breakdowns on the Internet before I understood just what was going on by the end of it.
I guess when I think sandbox, I inevitably compare it to Halo at it's best. Something like the Scarab encounters in Halo 3, or the famous brute packs in Crow's Nest. The whole verticality and swinging around from space to space was really, really cool. But there were only a small handful of times that I felt they really nailed it in-game. The combat itself is kinda distilled, almost all the enemies are just bullet sponges and have very little feedback, if any, and most of the weapons work more or less the same. The powers are fun to use, but they didn't really feel all that necessary, and I wish they would have played up elemental weaknesses or one-two-type combos more. The AI was functional, but ultimately forgettable, even on the higher difficulties :/
Infinite exceeded my expectations by not being horrible, and actually being really enjoyable, but in a few years time, if I decide to go and play through it, I won't be doing it for the sandbox combat, it will probably be for the story and worldart.