My main issue with the Artilarist is the turret not scaling well, like the other combat "Pets" do. I like the subclass otherwise, though I suppose you'd have to use the Turret for something other than "an extra attack". Seems like it is more of a support role, like putting it up to cause distractions while you escape or whatnot. Set it in front of a door and let it keep out the bad guys. With 5 times lvl, it's fairly robust as you lvl up. And even then, if the baddies charge it and start getting close to killing it you can just blow the turret.
However, it can climb, so if you have time to get your turrets into position, then they can lay down some fire on a single enemy with the Force Balista, act as crowd control with the Flame thrower, or grant endless temporary hit points to the group. And once you hit lvl 14, they grant half cover, which the rules don't say can't be used for Melee, the attacker just has to be on the other side of the field. Couple that with Temp HP every round and a second turret with the flamethrower, and a smaller party could take on a swarm of enemies without much difficulty. Add in a Paladin for the Saves, and you've got a powerful group, right there.
The damage kind of scales, in that you can have two turrets at lvl 14. and can use one bonus action to activate both. That's not nothing, though, as the Force Balista pushes creatures back 5 feet, so in a group, being able to both attack and push 2 creatures into different places is actually pretty dope, especially for breaking grapples or allowing a disengage without causing opportunity attacks. And you can move the turrets around at the same time. Give the Artificer a Thorn Whip (which I imagine as a grappling gun), and you can move three enemies around the room every round.
I've changed my mind. The utility of the turrets being a "ranged pet" having crowd control, single enemy movement and being a source of Temp HP is pretty awesome. It gets even more so when at lvl 14 it essentially functions as a party wide +2 to AC and Dex saves, and you get a second Ranged Pet, which adds just that much more utility. Keep the party pumped with temp hp while laying down fire on the crowd, or double up Force Balistas for fairly effective crowd control or BBEG suppression. All of which simply uses a Bonus Action.