The part that is kind of weird but, once I got used to it, extra satisfying is that you'll never be "worse" than in the beginning, before you level up some soldiers and get the first round of weapon upgrades (magnetic rifles). But it can be frustrating in the beginning when you're not sure the right build order and waste precious resources on things you don't need right now; you'll end up having spent resources on a workshop or something then can't afford to get build the weapons tech you so tirelessly worked towards for another month...
For Xcom 1, I think I had to quit and restart campaigns twice before I figured it out - just got to insurmountable positions and figured "well, the aliens won this one - let's try again". Once you "get" it though, its a wonderful game.