Random thoughts:
Played through a classic non iron man, (wanted to feel out the game) and it's really fun. Meld forcing you to play a little more aggressive for bigger rewards is a amazing feature. With the added maps, I never felt I played the same map twice. Some were familiar ones from vanilla, but i think almost every map was a new one (though the Exault covert hacking 2x towers got a little repetitive).
The aliens have better AI, and Exault missions which have even better AI... well they would be very tough without the global disarm button you get.
Mechs... I love watching them every time they kill something especially with the fist. I didn't try flamethrower, EMP sucks. My usual squad in vanilla was 1 tank assault, 1 blitz assault, 1 support, 1 heavy, 2x snipers, and the snipers did all the heavy lifting. Now I use a mech as the tank, and with self healing meld on everybody else, I save all my heals on him. Support is now speced for smoke as they will get 2x uses out of a medpack. Rigging means I can field a lot more grenades, and with Exault missions having no penalty for using them, I make Micheal Bay proud during my fights with them.
With meld, and everybody getting the heal one. Supports are now Mech Healers. Speaking of Meld, the invis skin is too good. It means you can scout without fear of waking up another cell of baddies and it means if you find them you get the drop (either start them off with a shot from a sighted sniper, or let them find you). Fun combo skin + sniper skill that allows full cover in 1/2 makes all cover invis you. I don't see any reason to get the defensive mind Meld, as the damage one knocks like 1/2 the life off, even if the enemy fails... and it's cheaper.
The 2 bonus counsel missions feel kinda cheep. One you get a leveled up heavy and a LOT of elurium + alloy. The new one you get 4x Psi soldiers... rape.
All in all, I thoroughly enjoyed vanilla and I love EW. Though I do agree, knowing the personality of the head engineer, when he causally suggested lopping off arms and legs to make a mech soldier, I was like... sup?