I guess I'll take a whack at this.

First of all, yes, this mod makes the game a lot more difficult. But it does so in strange ways that not everyone will find fun to play around with. You basically lose most tools you normally have to deal with situations from the base game and don't really get anything back for it while the basic way you need to approach encounters are changed dramatically.

What I mean by this is that aiming sorta sucks, at least early on. Use heavy weapons or shotguns and bring them up close. Ignore the hit chance because misses can hit and yes I understand that is unintuitive. Don't expect to hit much with assault rifles or even sniper rifles with low ranked troops. Even if you do your first targets will be Ceasans and they have personal shields which have no visual effect making it really hard to understand what's going on when you unload 6 shots into one point blank and they took no damage. Many of the weapons are either objectively worse than other options, situational in usage, or only useful against it's weakness. All of these things you will need to lose campaigns to learn.

This design philosophy is abundant throughout the entire mod. you will have no idea what's going on when you see something new and even after you understand how it works you may not know how to counter it or understanding it would require you were the creator yourself. Counters may be found later on through tech but some things literally have no counter at all. Sometimes the best thing you can do is run to live another day. The only way to wrap your head around the resistance mechanics and how to play against them will be trial and error. Soldiers will die while you learn and this will cause you to lose campaigns. Get used to it.

Flashbangs don't work. Even the advanced ones for some reason. This means that entering rooms or areas with camping enemies who are out of line of sight is sometimes impossible. Using shields helps but not if they are at a 90 degree angle. This is made even worse by the ai being programmed to always hide in exactly the right square that you will have the hardest time getting vision on. There's only two ways to deal with this really. Get power armour and barring that blow up the entire map. Use explosives liberally.

Enemies have a perfect understanding of the mechanics down to the exact math behind it and will make decisions with this knowledge, effectively meta gaming you while you have very little ability to do so yourself. An example of this is when they will choose to use certain weapon types or grenades against specific targets with the type of armour that will take the most damage. They know your weaknesses and exactly how effective they are against you while you'll never have that type of encyclopedic knowledge.

So basically what I'm saying is this mod removes many of the tools you will need to deal with bad scenarios, it introduces many new bad scenarios, and you might not be able to intuit the correct solution to a scenario without bashing your head against the wall which essentially means restarting and making new campaigns. You will fail many times before you can win a campaign or even get through a phase. You are not the chosen one who will win on the first try. It's just not doable.

With all this being said there's nothing quite like coming across the complete ♥♥♥♥♥♥♥♥ that this mod can throw at a squad and coming out on top. Coming up with new and out of the box strategies that you'd never need to use in the base game is very rewarding.

If you expect this to be like LW for xcom games you've made a mistake. LW is designed by people who intend every problem to have a tool to fix it and actively tries to reward problem solving skills. This mod is created by a sadist who probably loves to watch people get angry over his arcane designs and a lot of the time will reward pragmatic decision making more than problem solving skills. There are also a few bugs and problems that hurt the mod badly in later stages.

This mod is not for everybody. In fact I don't really know who it's for. After you've thrown your tenth stun grenade at a common sebilian solider who finally goes down to the gas while the loading tips tell you that resistances get lower after each resist you'll probably feel more anguished than relieved. I really wish I could say more about it that sounds good because a lot of work went into it and despite all it's flaws I do enjoy the challenge this mod presents when it's working correctly. It just doesn't feel like it is a lot of the time and it seems like that is the intended feeling.

Here's some advice that will genuinely help. Save scum. You probably have a life to live and spending hundreds of hours learning how mechanics work with no way to learn them otherwise just makes no sense. You'll probably not find it fun either or at the very least get frustrated. Some people may get angry at me giving this advice but you can totally just go ironman after you've learned how things work.