I've been avoiding the video games part of the forums until I could finish this (and since we're in the middle of moving into our new house, that took a while).
So finished it on Heroic, which is what I play Halo games on. Some of the early boss battles were pretty rough and my teenager at one point asked if I should turn it down to normal, so clearly I should have raised him better.
I concur with what Menace said about the gadgets - for like 90% of the game I would swap to the tracker, fire a couple, and then go back to the grapple. I started using the dropshield on occasion in the last third, and only really ever used the boost in one specific encounter with two Hunters where I went in with the wrong weapons and needed to get around quickly. On the other hand, grenades, meh, I never really ever selected specific types of those, I just threw whatever was ready.
I enjoyed the story but I'm a geek for lore and audio recordings and whatnot. I think Princess Echo the pilot was a bit one-note through most of it, and Escharum was a great character for the last 0.5% of the game but a goddamn caricature for the rest of it. It's certainly not the best "Infinite" story, but Bioshock Infinite is still the benchmark for me anyway.
I'd give it about a 9. I don't give half a tit about multiplayer so this is just the campaign - and damn, was it fun to play, and the story wasn't bad. The grunt chatter and propaganda towers provided necessary levity, and I'm definitely down for the next story DLC. Certainly the best campaign 343 has done.