Well, it's about as difficult as DF with sparse tutorials, and minimal graphics about the same as ASCII in detail.
The mouse has a lot more use than in DF, so it will take much less time to learn how to navigate.
The component, missile, and ship/PDC designing is far more complex compared to DF's ease to set up a junk military, but that's also a great benefit, since you can design whatever the hell you want. But it does take much, much more time to set up a working military compared to DF.
As it is turn based, you should not feel as overwhelmed as DF unpaused. Though it's a minor effect.
As you said, this is a spreadsheet simulator. You'll be looking at a lot of white background and there will be around the same amount of detail as ASCII DF.
The combat is completely different to most 4x games. It's not any sort of "PEW PEW CABOOM" but more like "Archer class missile has impacted the hull of USSF Iran. Warhead explosion size 10 detected." In other words, it's like Dwarf Fortress in a 4x game.
The game is as streamlined as DF. Meaning it's very clunky in a multitude of ways.
While this sounds bad, if you have ever played a 4x game before, and want more, this game without a doubt offers about the most you can get out of a 2d turn based 4x game in my opinion. There's without a doubt room for improvements, but there always is for any game, of any type.