I'm a believer in the "Artemis master race." It is an incredibly versatile weapon, and in good hands it is incredibly effective at more than the alternatives can offer, if you can find a good Artemis gungineer, you can effectively counter many builds, even if other builds have higher killing ability, you need to keep in mind how effective this weapon can disable other ships.
Some facts about the Artemis.
Also the Artemis does not have an arming distance, this means you can pair it with a Gatling, a Hades and a Mercury.
Load it with burst ammo, unless you intend to fight at extreme range pairing it with Mercury, then you want to load Lesmok.
Shooting burst with an artemis will destroy a small component (Light guns and turning engines.) in one shot, and two shots for heavy weapons.
If you have an Artemis gunner who is very good, he can shoot inbetween both of a Galleons guns and disable both guns in two shots, so of you're in a pyramidion against a Galleon left broadside, you can disable all three guns in one clip and have left over.
Gatling Artemis pyra counters Metamidion, your Artemis gunner disables enemy Gatling as primary target, then the mortar, while your own Gatling strips their armour, the metamidion becomes ineffective at its primary job, the Artemis deals a reasonable amount of permahull damage too, often it will require two armour breaks to kill an enemy I they have a good engineer, but this shouldn't be a problem if the enemy can't shoot you. So long as your ally can handle the enemy team mate, a gat art pyra should out do a metamidion with mediocre shooting.
Artemis counters Goldfish, two shots and the main gun, the life blood of the goldfish is gone, they may try for side guns, but your Artemis gunner should still have shots left in his first clip left over to take care of that.
There are however downsides!
The pilot of an Artemis weilding ship needs to be aware of all enemy ship positions and aware of his surroundings in general, if a kill ship manages an ambush, it's not likely you can recover and take control of the engagement, this however applies to all ships and builds.
The gunners need the ship to be stable, to do this, stop turning and burn kerosene or moonshine for a split second, this will.hold the ship steady and make shots for the gunner much easier to judge.
If playing at range, many Artemis shooters may zoom in, doing this makes it much harder to tell of the ship is moving in any direction, forwards backwards, left, right, up, down, so if at range, keep constant comms as to which direction you're going.
If mid to close range, Artemis shooters should try to avoid zooming in, this will help them be aware of their own ship, and enemy ship movements, making trajectory judgement easier.
Close range Artemis in brawling is not as easy as you may think, although the arcs on an Artemis may be good, the gun has a relatively slow turn rate, which makes aiming in brawls tough, the pilot should focus his ship arcs rather than rely on the Artemis turn speed.
Artemis needs to hold the high ground! It has bad upward arcs, so make sure when engaging you have the higher or of not higher, the same height!
Out of all of that the most important is keeping the ship steady, and making sure the Artemis gunner knows to target weapons and engines, timed shots to match with hull break, in my opinion should have less priority than disabling weapons.
Also a final note: Artemis is for left handed gunners!!!
Remember gatlings, flaks, mortars, Hades can't kill of they can't shoot, and the Artemis can very effectively disable those guns at very reasonable ranges.
Throw the meta of kill builds out the window and accept, Artemis as your new god.