Also: Holy shit, complicated.
At first blush, yes. But only if you really want to understand the math behind what happens. Otherwise, I think Dominions is actually pretty straightforward. What there is to learn, is a ton of small rules that, when they scale up create problems if you don't know what's going on.
So, for example. When you q units to build, there's two ways to do it. You can spend up to the available resources of the province and repeat that build order every turn....
Or you order MORE units than the province resources can support per turn, and basically spend the gold ahead of time.
How this manifests in game though is a huge disconnect between your "Income" and "Upkeep" values. You'll look at it thinking you should be making 1000 gold per turn when you're only making 600. That's because the game doesn't state your recruitment costs anywhere.
Not a huge deal for games in their first decade or so.....but when you're playing on a 400 province map and you're 20 years into your game, you can easily lose track of where you're recruiting and end up going into the red. Then add Unrest reducing Income sprinkled liberally across your empire and yeah....
The other thing that takes some time to understand is how Dominion works, because there's lots of little rules and effects there. (Your troops have less morale when outside your pretender's dominion. Death dominion increases the likelihood of getting diseases afflictions. Pretenders don't automatically resurrect outside of their own dominion. Things of that nature.
Dominions isn't like, DF complex though. It is wonderfully supported by tooltips almost everywhere, which really helps. If you don't bother to try and understand what's going on during battles, Dom is fairly easy to learn. Intermediate level is where you start paying close attention to how your armies are built and what AI orders they're given.
Also, protip: Unless you're going to save scum, do. not. sweat. your. heroes. There are 100 ways for a commander to become crippled. I've done extensive testing through save scumming, and the simple fact is big battles = your best commanders getting trashed. They'll get cursed. They'll get horror marked. They'll lose an arm or become crippled. They'll get diseased. Early game it's not as likely (although the random Deer Shaman or w/e cursing/horror marking your guys is annoying as shit.) but late game the AI will, not necessarily kill them but reduce their effectiveness.
Almost all nations have ways to keep your heroes in tip-top fighting shape, but most are mid to late game solutions. For me heroes are one of the best parts of Dominions from an RPG aspect, but they're also the reason the game causes stress. When you've got a whole army of your best heroes bearing down on your opponent, and half of them exit the fight with one foot in the grave, it leaves you feeling kinda mad. There are only two things you really can't fix when it comes to heroes, and that's Cursing and Horror Marking. So just a fair warning. Early on, heroes seem amazing and nigh-invincible. Mid game though their frailties start to show.
(As an aside, fucking Twiceborn. Why, oh why, would I want a guy who is feebleminded, mute, crippled and missing an eye to resurrect in that state? A feebleminded wight mage? WTF? You can't even reliably get them to die in your dominion without specifically arranging an enemy province in your dominion for them to go zerg into. Such rage. It really undercuts my desire to play Sceleria, my favorite nation, because all my reborn heroes end up just as crippled as they were at the time of their death. I kinda figured Twiceborn would waive some of the stupid shit like Feebleminded.)