Maybe it's the normal setting but i'm blowing through this game so easy it's really no challenge.
I haven't even done the first alien base mission and my guys nearly have levelled out (and i just researched laser weapons and have aquired Plasma Rifles from a stunned Muton).
My squad contains a (now) once upgraded MEC Trooper and 2 Gene Soldiers (one Sniper with enhanced Leg Muscles so he can jump high on obstacles to get a better view.. looks awesome when he leaps around) alongside normal Troopers.
What i have noticed is that the MEC seems inferior to troopers and Gene soldiers because the latter keeps the skills and gets the bonus from the enhancements. However the MEC can really take some punishment and is near indestructible in the early game so i used him often enough as the advance scout to spot the Aliens.
Maybe later in the game when Elite Mutons and the Alien Walker appear he will be sorely needed, let's see.
I've now encountered the Exalt group and have sent out my first agent to infiltrate them, really like this add on.
So far i'm having a blast discovering all this new stuff and i've still to encounter any of the old maps.
Well done Firaxis!