The Lord Of Skulls is still not an awful choice. Even a bad superheavy is still a freakin' superheavy, and it has an awful lot of firepower.
The Kytan is the same price (£) but cheaper (pts) but is damn near as capable. Rear armour 11 rather than 10 makes you immune to bolter fire, and its melee stats are massively better. You do lose the hellstorm template, though, which I will admit is the main downside - hellstorms are scary as against massed infantry.
The Gorestorm cannon is nice. I wouldn't buy a Daemongore Cannon upgrade - yes, S9 instant death is awesome. But is it better
enough to justify Gets Hot? Because you've got decent odds of this gun failing to fire at least once in a game when you want it to, and (lacking stomp) this is the Lord Of Skull's main crowd-control weapon.
S8 is generally enough to cause instant death anyway, and whilst S9 may be better at antitank/antimonster, your hades gatling is better at both than either, and if you're in template range you're probably going to be in range to apply chain-cleaver to important bits very soon anyway.
The Ichor Cannon isn't bad but again you're giving up a lot of infantry-killing power - that you need - in return for a S10 AP2 blast. A good trade if expecting terminators, centurions and thallax, I guess, but not as standard practice.
The skullhurler is a decent choice. S9 blast is awesome, but Gnaw gives it good performance against infantry in cover, jinking bikes and that sort of thing. Is it good enough to justify giving up 12 krak missiles a turn? Depends what else is in your army.
The biggest problem is his melee stats. WS4, I3, A4 is a bit like the problem with the Scythed Hierodule - you hit after astartes dreadnoughts, knights, wraithknights, etc - things which stand a decent chance of chopping important bits off you.
Ultimately, this could be worse. Under normal circumstances, a charging Imperial Knight will cause serious damage - taking an average of nearly 6 hull points off you. Thanks to Fuelled By Rage, you will then unload a faintly ridiculous 10 destroyer attacks back on it, and do enough damage to kill it twice over.
The problem is that you're outnumbered 2-1, and the second knight will kill you before you get to attack....
You will need to figure out how to leverage the firepower of your hades gatling and/or the rest of your army to gut a knight at range - which isn't impossible.
One thing to note is that you can make a Lord Of Skulls much more effective if you support it properly.
It is a daemon, which means all the normal shennanigans like Grimoire of True Names and Cursed Earth work normally. In a Daemonkin army, Daemon becomes Daemon Of Khorne, giving you the Blood For The Blood God rule, allowing for extra attacks or summoning daemon packs.
Also its bad that Chaos have to take a financial kick in the bollocks by relying on the Forge World Crutch in order to be somewhat competitive. I'd much rather just run my 9 Nurgle Obliterators and Melta the crap out of enemy armour with 1 unit, burn the masses with another and go HQ hunting with another.
You don't necessarily need to. After all, if you really want to be that guy, field fifty-odd solo obliterators and mutilators as an unbound army and watch your opponent try and cope with that....
If you like the Lord of Skulls, take it! The model is unique and people aren't used to seeing them.... if you measure your army purely by 'what can take on the latest tournament thing' you'd never have got a 7000 point chaos army together.
I've been trying Hierodules recently, and whilst they're massively underpowered compared to 'modern' gargantuans and superheavies, they're still fun and scary as hell for people not used to fighting them!