I searched for a bit and got a bunch of results, but not a lot of what makes G&K changes special and how they affect the game's combat feel overall. Specific discussions here can be spun off if they get extremely in-depth, but I feel that a general combat milieu thread would be nice.
I felt that with all the changes made to G&K's tech tree, unit mechanics, and unit distribution, there'd be a profound change in the combat milieu since pre-patch Civ V. That proved to be correct. Here are some overall impressions:
1. The interplay between Swordsmen and Spearmen and the choice to go for one or the other is a more interesting decision now. Make Warriors-Swordsmen or Spearmen-Pikemen is no longer a done deal, and it's made more complicated because Pikemen don't upgrade to infantry but to cavalry. This meant that my Immortal spam as Darius led to me having to reconstitute the main bulk of my infantry during the Renaissance.
2. Composite Bowmen constitute a continuous improvement line where ranged combat matures alongside melee combat with no period of melee combat superiority; and it's situated with Construction, which is a key economic tech. I'm not sure how I feel about that. It diminishes the role of melee in general in war, unless you don't have a lot of troops.
3. Siege units are much more powerful, and they're selectively powerful against cities. This is a good change. Additionally, the AI favors attacking nearby melee units over siege units; so if you're bringing along a Siege unit to do most of the city damage, it pays to serve up melee units for the AI cities to target.
4. I'm not sure if the promos have changed, but the new combat milieu makes it feel as if it has. Units lasting longer means that Charge (+33% vs. damaged units) is more valuable. It boosts Bushido similarly, since you can leave a unit as an attacker for longer without losing it.
Moreover, it makes the defensive value of promos and defensive promos more inviting. Whereas in Civ, I favored the Shock line of promotions to protect my melee troops from fire while they closed (and to help them massacre AI troops on open terrain), in G&K, I prefer Drill; and in particular Drill2+Cover or Drill2+City Raider, which now adds +50% vs Cities. A Drill/Cover promoted melee unit on a hill can Fortify and attract a lot of ranged fire turn after turn without dying, particularly if it has an adjacent Medic2 to provide Discipline bonus and healing. A Pikeman/Immortal attracting AI fire like that is practically, well, immortal.
5. Askia's UA is really entertaining. By that, I mean the promos part, not the bonus gold part, which was left unchanged. War Canoe and Amphibious applying to all his units doesn't just make the Marine obsolete; it makes all of Askia's units Marines - every single one. Faced with a slog of hills and jungles towards a well defended city, I simply embarked my Riflemen and took it from the sea. Awesome.
6. Mounted Units!
Since I was forced to use a lot of them, I found to my shock that the Lancer, and the UUs associated with it - Sipahi and such, have been somewhat improved. They no longer have any unique defensive penalty; in fact, they're pretty much Better Knights. This marked a sea change in my land army strategy; mostly to make it more interesting, but also to greater efficacy.
Since I no longer use melee units to assault cities directly, and ranged units don't always do enough damage to kill enemy units, I have come to rely on cavalry to provide the finishing blow, particularly for fleeing wounded AI units, enemy siege or ranged AI units, and so on. Once I control the land, melee+siege operations can begin (behind a screen of cavalry, natch).
The Sipahi is very good at doing this because it has +1 Sight and can spot reinforcements or fleeing units from a ways off, and has the +1 speed to effectively hit-and-run without giving the enemy unit a chance to retaliate, if it's melee and the conflict is on flat terrain. If nothing else, you can give it Sentry and use it as a powerful Scout. Very useful for exploring foreign continents on Open Borders.
The Conquistador is even more so. Not only can it take out barb camps, see everything; it can also found cities if you happen to find a fantastic spot.
Lastly, the Cataphract from the Byzantines combines all the things I want from a melee unit except that it makes Byzantine Swordsmen unnecessary. Since I'm never going to attack a city with a melee unit until it's got no hp, its one downside essentially doesn't exist. It can even serve as range fodder since it benefits from terrain bonuses.
I felt that with all the changes made to G&K's tech tree, unit mechanics, and unit distribution, there'd be a profound change in the combat milieu since pre-patch Civ V. That proved to be correct. Here are some overall impressions:
1. The interplay between Swordsmen and Spearmen and the choice to go for one or the other is a more interesting decision now. Make Warriors-Swordsmen or Spearmen-Pikemen is no longer a done deal, and it's made more complicated because Pikemen don't upgrade to infantry but to cavalry. This meant that my Immortal spam as Darius led to me having to reconstitute the main bulk of my infantry during the Renaissance.
2. Composite Bowmen constitute a continuous improvement line where ranged combat matures alongside melee combat with no period of melee combat superiority; and it's situated with Construction, which is a key economic tech. I'm not sure how I feel about that. It diminishes the role of melee in general in war, unless you don't have a lot of troops.
3. Siege units are much more powerful, and they're selectively powerful against cities. This is a good change. Additionally, the AI favors attacking nearby melee units over siege units; so if you're bringing along a Siege unit to do most of the city damage, it pays to serve up melee units for the AI cities to target.
4. I'm not sure if the promos have changed, but the new combat milieu makes it feel as if it has. Units lasting longer means that Charge (+33% vs. damaged units) is more valuable. It boosts Bushido similarly, since you can leave a unit as an attacker for longer without losing it.
Moreover, it makes the defensive value of promos and defensive promos more inviting. Whereas in Civ, I favored the Shock line of promotions to protect my melee troops from fire while they closed (and to help them massacre AI troops on open terrain), in G&K, I prefer Drill; and in particular Drill2+Cover or Drill2+City Raider, which now adds +50% vs Cities. A Drill/Cover promoted melee unit on a hill can Fortify and attract a lot of ranged fire turn after turn without dying, particularly if it has an adjacent Medic2 to provide Discipline bonus and healing. A Pikeman/Immortal attracting AI fire like that is practically, well, immortal.
5. Askia's UA is really entertaining. By that, I mean the promos part, not the bonus gold part, which was left unchanged. War Canoe and Amphibious applying to all his units doesn't just make the Marine obsolete; it makes all of Askia's units Marines - every single one. Faced with a slog of hills and jungles towards a well defended city, I simply embarked my Riflemen and took it from the sea. Awesome.
6. Mounted Units!
Since I was forced to use a lot of them, I found to my shock that the Lancer, and the UUs associated with it - Sipahi and such, have been somewhat improved. They no longer have any unique defensive penalty; in fact, they're pretty much Better Knights. This marked a sea change in my land army strategy; mostly to make it more interesting, but also to greater efficacy.
Since I no longer use melee units to assault cities directly, and ranged units don't always do enough damage to kill enemy units, I have come to rely on cavalry to provide the finishing blow, particularly for fleeing wounded AI units, enemy siege or ranged AI units, and so on. Once I control the land, melee+siege operations can begin (behind a screen of cavalry, natch).
The Sipahi is very good at doing this because it has +1 Sight and can spot reinforcements or fleeing units from a ways off, and has the +1 speed to effectively hit-and-run without giving the enemy unit a chance to retaliate, if it's melee and the conflict is on flat terrain. If nothing else, you can give it Sentry and use it as a powerful Scout. Very useful for exploring foreign continents on Open Borders.
The Conquistador is even more so. Not only can it take out barb camps, see everything; it can also found cities if you happen to find a fantastic spot.
Lastly, the Cataphract from the Byzantines combines all the things I want from a melee unit except that it makes Byzantine Swordsmen unnecessary. Since I'm never going to attack a city with a melee unit until it's got no hp, its one downside essentially doesn't exist. It can even serve as range fodder since it benefits from terrain bonuses.