Been getting ahead with things. First of all, the gameplay does get a LOT faster than at the start, once actual flying enemies (not puny helicopters) show up and the Defense ACs (those tank-tread things) start coming with shields (make them considerably better at soaking fire, but you can get behind them if you're fast), along with enemy sniper cannons, missile batteries and howitzers. Not to mention actual enemy Armored Cores, obviously. Obviously not the same kind of speed as AC4 series where combat was about not getting hit at all because you were a super-sonic whirlwind of destruction, but it's still faster than the PS2 era games. Quick Boost (now called High Boost) is still in for example, and one of your most important tools for survival. Because Energy is more limited this time around, so is your Quick Boost, which you now use to dodge missiles at the last moment and rapidly shift your position so you can avoid enemy fire, but you must conserve it. Instead your standard means of increased mobility comes from WALLS, as Armored Cores can leap up, off and along walls at High Boost speeds without the energy cost, which is probably why ACs are so small now and more buildings indestructible. It also presents a more involved form of environment you need to adapt to, because now the difference between an urban and more open levels is extremely notable (especially due to how vertically limited you are) and you need to adapt your tactics accordingly.
You also take a lot more hits this time around, but damage resistance has been upped to eleven. I play a mobile medium-heavy bipedal AC, but I can still have a ton of shit hit me before I start feeling the heat due to smaller weapons simply bouncing off. Compared to previous games, damage resistance types are of paramount importance, with enough resistance making you almost immune to the damage type. It's also why damage has now been divided between Kinetic Energy, Chemical Energy and Thermal Energy, to create a fuller rock-paper-scissors circle. It can get a bit annoying though, since some AI ACs have ridiculously high resistance to Chemical and Kinetic Energy, while Energy weapons seem to just suck donkey balls. Might be that the pendulum has swinged more in favour of the Tank legs again, after the supremacy of medium bipeds in AC4. In general it seems heavier legs are better, my AC is mostly medium parts but the legs are heavy, and it has lead to better turning and stability with no loss in Boost mobility.
Probes are definately useful, because you need to move fast in order to get the best rating. And in order to do that, it pays off to be able to find any bastards hiding. There's several missions where you have to locate enemies that are hiding.
There's also a new melee weapon now, actual Physical Blades. So far seems to me they suck, but melee in general is a lot weaker now it seems. In general there's a lot of new weapons, though I'll start testing them out once I get everything unlocked and can start getting creative. Getting cash isn't hard (you can get 500k with a very easy 1-on-2 AC duel where both of the opponents have paper-thin armor), it's just the part of getting things to the shop in the first place. So far I've only played Order missions (approaching #50), so I don't know how Story missions would change this.