Seriously. I'm mostly just putting this here to link because I'm tired of typing it out on half the ork army lists I visit. Please don't use it because it sucks in comparison to the bog-standard
CAD which is wonderful for us greenies given the prevalence and staying power of our boyz.
Ork Horde The Good: + 3
HQ slots ((Don't let this squig-snake tempt you. You'll see...)
+ 9 Troop Slots (Does anyone actually need 9 troop slots this side of Apocalypse?)
+ Free Hammer of Wrath on big boyz mobs
+ Re-roll Warlord trait if using the Ork table.
The Bad: + To get said Hammer of Wrath, the unit must be above ten boyz on the charge (dubious at best)
+ You also have to roll
2D6 => 10 inches for your charge (even "dubious-er"

+ The Hammer of Wrath attacks are only performed by boyz who make it into
Base Contact with an enemy model, and happens BEFORE pile in moves (see what I'm getting at here?)
+ Your Warlord does not get re-rolls on any of the Rulebook tables (wow, rude right? sometimes you'll want to roll on those tables depending on army comp and gametype)
The Ugly: + The Hammer of Wrath attacks are S3
AP-
If you don't feel kicked in the teef by now, let's go over the good ol' plain Jane vanilla bean Combined Arms Detachment:
The Good +Re-Rollable Warlord traits on any table you want (including the Ork table!)
The Great +Objective Secured on all of our Troops. This is god tier for orks. With decent rolls, a Nob all by his lonesome with a bosspole will hold his own forever (he also cant allocate wounds on himself for Breaking Heads rolls (aka the roll you want) so its like a free pass.) Also our troops can come in 30 man (or 300 man) near-fearless (or actually fearless) blobs, take 4+ armour, trucks that can go 24 inches a turn (which ALSO gain Objective Secured), and have access to cheap
FNP and (semi)cheap 5++.
The Bad +
... crickets... The Ork Horde detachment is questionable at its best and literally useless at its worst (oh no, my boyz unit is at 9. oh no, I
only rolled a 9 inch charge, oh no, my less-than-a-handful of S3
AP- hits did literally nothing).
The Combined Arms Detachment is great all the time. Re-rolling all Warlord traits basically guarantees getting the Strategic Trait you want if you take Thinking Cap (nets you 4 rolls, bro) if that's your jam. If you still have boyz, grots, or trucks on the board they steal objectives from anyone that isn't also ObSec, and if you don't have any (even lone) Boyz, grots (haha), or trucks on the field then something has gone horribly wrong and ObSec isn't gonna save you now.
But in a lot of circumstances, ObSec
will win you games. Because not only can you make last minute Objective captures, but you can literally
STEAL OBJECTIVES FROM THE OTHER GUY if he isn't sitting on it with his Tacs or Firewarriors or whatever (and orks will turn em to paste anyway). Worst case you contest the objective and neither of you gets points. But that's a pretty damn good "worst case scenario" if I say so myself.
The only drawback is you only have access to 2
HQ slots instead of 3. Well this is where you pack up your cares and throw them overboard because you're an ork dangit. Just take two Combined Arms Detachments. Sure, it costs you 4 troops, but really, any higher than 1k you really should have 4 or more, and you also end up with 4
HQ slots (which if my math is correct, is 1 more slot than the Horde detachment). And you can keep taking detachments like this
forever. That's just my two teef on the matter. Speak up if you object, I honestly would love to know if there is actually any use at all from this formation because the way I see it, its bad. So if you can redeem it, more power to ya.