Same thing happened to me when I switched to Classic Ironman. I think I screwed AT LEAST half a dozen playthroughs before I was finally able to complete Classic Ironman. I still haven't completed Classic Ironman without taking a casualty or without losing a XCOM member nation which is something I can comfortably do on Normal Ironman.
I think the biggest difference is that in Classic mode, you HAVE to be in full cover 99% of the times or you're screwed and you need to have AT LEAST 2 (I'd recommend 3) soldiers of each class type ready to go at any time because injuries happen regularly and with Enemy Within you have to go on a mission almost every day till you take care of Advent.
My current game is going... well... I mean, lol, I had to skip a mission because I literally had no soldiers available and Mexico was gone. But now my first nexus is being built and the 5 satellites are already on the way. Laser rifles are a thing and the rest are being swiftly researched.
If the base defense mission doesn't come at the worst time possible (I just ruined it, didn't I?), I think I can survive enough to stabilize myself into infinite money and then just hold on until plasma weapons give me the win.
But yeah, deciding to shoot while in half-cover is such a difficult call. You have your soldier at half-cover, 65% chance to hit the alien, you can't move to full cover. It's such a hard call.
Heh, that's me for Classic -> Impossible, although I've managed to get through Alien Base once on Impossible Ironman (felt the hard part really is getting past the rookie and initial country panic spam)
Wondering if a Civ-style spread of more difficulty settings would be a good thing.
Edditing the .ini of Long War a bit showed me that while being able to do a modular difficulty setting might be useful and fun, it's also a kind of gateway drug to just making the game too easy on you all over again.
But my ideal difficulty seeting right now would be Classic, but with normal Thin Men.
Every time I miss a shot on a Thin Men, I look at the soldier who missed and kiss the screen.
You were brave, my flower, but you failed. And you're probably dead now.
Oh yeah, that's nice. It's crazy how much firaxis have come to respect those people.
Really nice stuff happening here.