*** Edited by AC ***
In our experience it is a challenge to play Orks.
Main reasons seem to be.
Reliance on CC. Units with a decent FF value are light vehicles and never live long.
The CC units usually do not get into CC at least not in numbers. Bad saves and no Inspiring Characters are just enough to loose the combat. It helps to keep the troops in a Fortress, but they cost twice as much as an Gorgon and have only have the save and die on a crit.
The fact that the initiative is three for marches makes it difficult to swamp your opponent. If you double only, he gets more time to shoot you down or move out of the way. On the other hand, if you move too far ahead he shoots you assaults you, does an clipping FF and breaks you. Gretchin can help, but don’t have to. For one they might not be where needed and for everyone you use to soak up wounds you loose the attack of an Boy or even a Nobz when outmaneuvered or careless.
There is really nothing that can create some covering fire, because you have to double to keep up with the advance, but also because of the risk to fail the initiative roll. So you hit on 6es and 7es. You cannot have enough dices to make that deadly.
Depending on the situation and opponent, you might be able to use ”sustained fire” and just in case take the BM. You still only hit on 4's and a save of 5 will not offer much protection against return fire.
The lack of good saves, "Mob Rule" and lower prices for bigger formations, tempt you to take bigger formations.
But than activation count goes down and you will be out maneuvered, outshot and assaulted where you do not want to be assaulted.
The Oddboyz could be good, but again you usually have to move them twice. Because of their longer range you find yourself often in the situation that one would be suppressed if you fail your initiative roll. So again it's shooting badly
or less.
A Stompa/Supa Stompa Mob is easily broken. If you have no Supa Stomp you might garrison them, so you might get them into action. If you have a Supa Stompa the can't garrison and don't do that much. At the beginning they will be ignored and than killed off when the rest of the army is routed.
If your opponent is cc oriented it gets better, but again, a ”real” cc army has units that beat any mob you might create. Also it is much easier to get in FF range than CC range and many armies are stronger in FF.
The FightaBomma cost only 150pts and you can make larger units, which is great - but you pay for it in lower number of activations. On the other hand the do not really justice to the term Bomma and when attacking a Squadron of Marauders, there usually are not many left to fire on the Bombers.
The Landa looks good on paper, but when you see what punch the passengers can have and what punch the passengers of a Thunderhawk can deliver.
So basically they can’t march, they are bad when shooting, they are not good in assaults, because numbers in CC are not as good as numbers in FF. They don’t have a decent save, no inspiring characters. They have mixed initiative and an average strategic value. The activation count as usually depends on your style, but is usually not on the high side.
So anything good ?
Style and imagery.
”Mob Rule” is ok and needed because of bad initiative, Nobz are good, Gretchins can be good. Some really fast units. Lot’s of Leaders.
”Power of Waaagh” is very stylish, love it for that. But an initiative of 3 for everything but … is really hard.
The kind of opponent makes a big difference.
When you look at the army and compare the formations/units to their likes of other armies, then overall, you might say there are within the usual range of cost.
But other armies have usually things out of ”range” (to their benefit) and do not consist of mediocre units only.
That’s probably the real point, the best Orks have are mediocre formations. There are no Annhilators, no Void Spinner (NetEA - the Epic-UK is pathetic), no Rough Riders, no Necron (all of them

, no Juggernauts - just take your pick.
The army is tuned for large formations (”Mob Rule”, lower relative cos of large units) that run towards the enemy and assault (”Power of Waagh”, lack of quality Firepower). Bad thing is that Epic rewards high activation count and that the units can often not make use of their size.
At least the way I see it.
Please note that is a rather dark picture, but it’s purpose is to show where problems are.
Potential remedies.
Bad Moonz or Heavies. Up to half the Boyz can be replaced with Bad Moonz/Heavies as a Boy , but 30cm TwinBig Shoota AP5/AT6 FF5 CC5
Landa Skorcha does only take 1 slot (like the SM Attack Bike)
Have a Warboss upgrade for a single Nobz in large or huge formations. The Warboss is inspiring for 25 pts each.
Blitz Brigades get option to replace GunWagon with Lung Bursta (Tank Bustas) a Gun Waggon with 45cm AP6/AT4 no transport, but 1 Gretchin and 1 BigGun (towed) for 5 pts each
THose should help without changing the character of the list.