It seems that encampment and its building still not worth building

[Duuk]

At least one city, preferably your Military/Industrial Complex, should have one. It's a nice synergy and you'll be able to kick out units insanely quickly enough to overcome losses, which allows you to play aggressively in attacking your neighbors and do semi-risky attacks that allow you to conquer cities faster by leaving units weak and vulnerable to counter attack, which will sometimes result in you losing a unit here and there.

 

[King Rad]

Bonus production.
Bonus housing.
...
Faster XP for created units.
...

This and the fact that you can build/buy units in a city with an encampment even if you only have one resource available. I also like to strategically place encampments so they can protect routes that invading forces would use to attack my civ - especially if this and a couple of walled cities can reach the primary invasion point. I play peacefully, so no major wars initiated by me. But in my last game, Seondeok and Shaka declared joint wars on me about 4-5 times. Because they are not the primary district, they are often also cheaper, especially in small border cities, than other districts, which can help protect them while they're developing. In fact, with the housing and production, I often find that this is a good district for the small startup in the tundra that I put there to get a resource. If I have both an encampment and an industrial district in a city, I often find myself building the encampment buildings for the bonus production rather than the workshop, since it also adds the housing and the ability to build units with only a single resource - possibly the one I settled the city for in the first place. Personally, while I also play sub-optimally, as @Karpius said, I like having more than one encampment. It often seems that just when I need to build something, if I only have one encampment with a barracks, for example, that city which is the only one I can build a knight in, is right in the middle of building a wonder or producing something else that I need.

 

[isau]

If playing as the Mapuche, an Encampment in a city with a Governor is pretty life changing. Even with just a Barracks or Stable your units have +50% XP which is enough to really make a difference IMO.

The strategy of building outdated units and upgrading them to avoid high production costs will no doubt be patched in the future. I personally do not use that strategy because I consider it broken, like the old Scythia "horse economy." If I was playing multiplayer I might be more willing to exploit it though.

 

[steveg700]

The strategy of building outdated units and upgrading them to avoid high production costs will no doubt be patched in the future. I personally do not use that strategy because I consider it broken, like the old Scythia "horse economy." If I was playing multiplayer I might be more willing to exploit it though.

I dunno, just seems like a variant of using gold to rush production, which I kinda miss. Always annoying to me to not be able to buy a unit I've already halfway produced for a halfway discount.

 

[SammyKhalifa]

I dunno, just seems like a variant of using gold to rush production, which I kinda miss. Always annoying to me to not be able to buy a unit I've already halfway produced for a halfway discount.

Yeah but it shouldn't be considerably cheaper than building or buying the unit outright.

 

[isau]

Yeah but it shouldn't be considerably cheaper than building or buying the unit outright.

This. It's basically an economy problem in that the cost to upgrade a unit is so much lower than the cost to build it or purchase it ouright.

IMO if you have 1 copy of a resource, then to upgrade, the cost to upgrade should be equal to the full cost to purchase the unit outright, to eliminate this loophole.

 

[Trav'ling Canuck]

Yeah but it shouldn't be considerably cheaper than building or buying the unit outright.

I expect we ended up with this system because the developers wanted to make it easy to upgrade old units when they become obsolete. The AI with un-upgraded units is a big turn off for many people.

Combine that with escalating unit production costs to avoid unit spam and this is what we get.