Depends literally how you use them. I don't like carriers (any of them) but thats because it descends to me swearing at pets. However used right? Yeah carriers work. They are not a waste of a ship slot; anyone who thinks that just can't use their ship!
Vo'Quv is slow but still useful. That Kar'fi though is extremely good. Quite literally again, how you use them.
Quick Edit: No, literally can start spaming out bird of preys with a vo'quv if you so desire. Nothing like scorpion fighters.
I have one of the most coveted ships in the game, the Jem'Hadar attack ship. it's dressed to the nines too. (has all the mk12 gear) When i got and fine tuned the Jem dreadnought carrier, i like it much better, I;m in the carrier most of the time. How good is it? Great fun! someone else actually named it for me. it's called the monster. Its just a different style of play, i am a tac captain, i use escorts and their variants a lot, but i also like the challenge of trying something different, it all in what you like. give it a shot in fair time, a month or so, you'll like it for the change o pace.
Carrier pets are slottede as equipment, like weapons or shields. You gain an ability on your tray to launch them, and you can do this an infinite number of times limited by a cooldown. They do not "wear out". Different types of carrier pets can be chosen for pure damage (quite a lot of it), target neutralization (tractors, energy siphoning), or even defense (shield repair). A hangar bay is a flexible and very powerful thing, and ships with hangar bays come with a variety of other capabilities. Escorts-with-pets like the Armitage or Jem HEC play differently than the heavy carriers like Atrox and Vo'quv that trade agility and some direct firepower in order to launch twice as many pets.
Soooo.. Are carriers good? I'd say yes, absolutely! Once you get the hang of them anyway. It does make your life somewhat more complicated since you have more things to keep track of.
Carrier operations are a very different playstyle from any other ship class in the game.
On top of that...there are different carrier types that also offer additional playstyle options.
Carriers can be classed into three general categories:
Pure Carrier (Vo'quv, Atrox, Jem Dread) -- very large vessels with a low turn rate.
Escort Carriers (Jem HEC, etc.) -- small to mid-sized vessels with decent turn rates.
Flight Deck Cruisers (Orion) -- large vessels with cruiser turn rates.
Pure Carriers rely mostly on their flight wings to apply damage -- this means you need to spec for carrier-specific roles, to include your space doffs (hangar bay cooldown, etc.). The carrier in this role is a support ship for the fighter wings.
Escort carriers fly into battle alongside their fighter wings and are damage dealers to some extent -- although they typically cannot do the same amount of damage as an actual escort class. Escort carriers cannot launch as many fighters as a true carrier, and the types of fighters it can launch are limited to the smaller types.
Flight deck cruisers fill both a light carrier as well as a cruiser role -- they are strong vessels with high survivability...and decent damage output. Like escort carriers, they cannot launch as many fighters as a true carrier.
Space combat in STO differs from player to player -- those players who fly escorts are going to look at carriers as a waste of time and ship slots because they don't entirely comprehend how powerful a real carrier -- when properly used -- can be. Although Carriers have been nerfed in the past (number of wings that can be deployed cut down, engagement range for launches reduced, fighter damage (esp. torp damage) reduced, and hanger bay recharge times increased...) they are still powerful combatants that can be game changers -- this is especially true if you are in a fleet action with more than one carrier on your team.
In PvE Carriers are very viable and can be fun to play if you like that playstyle. I have not PvPed in a while...I have flown a carrier in PvP in the old days (a Vo'quv) and it performed well...but there have been a lot of changes since then, and so I do not know how effective they might be today. My impression of PvP in the game at this point is that it tends to be escort-heavy, with a lot of fast-moving alpha strikes...for carriers, that is not an optimal environment. Carriers are most effective (I think) when going after larger targets, like cruisers and borg ships, for instance...
Bottom line -- carriers can be a lot of fun to play..but it is more of a personal choice, and the playstyle is very different from your "cloak, prep, strike" type of tactic.
there are 4 two-hangar crariers - the atrox, jem'hadar dread, vo'quv and kar'fi
the jem'hadar dread has assault cruiser hull (60k with skills), decent shield mod (1.15), high inertia so it actually turns as fast as the fleet excelsior. it's more offensively based than defensively based. you can use dhc's and turrets, but if you find yourself in a situation where you need to flee the scene of a tac cube wanting to eat your face your dps drops into the toilet very, very fast. if you cant maintain 100% uptime of facing your target on a ship that turns this slow you will probably find all beams a better option especially fed side, wher you can combine beams with a 180 degree quantum torp and have all weapons on your ship hitting the target 100% of the time while moving very, very easily. if you've seen the 9k dps assault cruiser youtube video - you can do the same thing on this ship and then add fighters on top. for both sides that doesn't start to make a substantial difference until you get elite scorpions though as it can't use b'rotlh
the vo'quv is mostly science/engineering slanted. it has a horrid turn rate, but it's unique pets are the deadliest in the game, deadlier than even the elite scorpions for most stf's. they will parse 4k dps on their own. the default vo'quv and fleet vo'quv can build fantastic shield tanks especially when combined with plasmonic leech. the mirror vo'quv not so much as you give up a lt sci for lt engineer as well as swapping a console slot to engineering. i happen to find having grav well 3, tykens rift 2, energy siphon 2, hazard emitters 1, science team 1 and tss2 on a ship that maintains 125 power and 80+ power to every other setting quite...insane. it's got decent hull, but not on the level of the jem'dread
the kar'fi 'm not impressed with. their unique pets pale to the vo'quv's. it is more tactically based, but the sheer dps difference in the pets actually puts the dmg output potential of the kar'fi lower than the vo'quv unless you are using dhc and can guarantee 100% uptime of your frontal cone on your targets without deviation. it's cloak is unique in that it allows you to keep firing all but torps and hangar pets, however it's a 3m cooldown. the fer'jei frigates didnt get a pass to their ai it seems, and their tricobalt damage is about as high as to'duj fighter quantums ie. quite low. they almost never use aceton beam and like to headbutt their targets a lot. the highest i've been able to get kar'fi to parse was 1.7k in an ise. better than 12 to'duj or 12 peregrines, but well below b'rotlh bops
the atrox i have not used. it has a more science leaning than the vo'quv, leaving you with only two tactical boff abilities. this can be somewhat limiting. it does have a higher shield mod by quite a bit (1.2 vs. 1.0 of the vo'quv) and turns almost imperceptibly faster than the vo'quv. it too can us dhc, but beams or turrets are your better choice. generally due to the poor manueverability i find beams preferable due to the 360 degrees of carnage you can put out with beam fire at will. from parsing other players i have noted that advanced peregrines outdps the advanced stalkers. but since we're on the klingon board i assume this ship isn't even in the running
there are single hangar escorts, but of them the jem heavy escort carrier is the best option kdf side. it's going down in price as more and more want the dreadnought instead. however klingon side you are better off with the vo'quv until you unlock elite scorpions at romulan tier 5. with elite scorpions you can pretty much run whatever carrier you want and not give up too much to the vo'quv assuming you can properly mange them and not end up with partial wings you can't refresh.