Rambling thoughts in stream-of-consciousness order because I'm barely coherent enough to post, no way I'm going to be able to sort this.
1. This may just about be the first time I've ever actually been intimidated by an Atlas. Holy sweet baby Jesus, when that smoke cleared, and I found myself looking into that grinning skull, I mean... WOW. Normally, I find an Atlas out on the field, and it's like "Ooooooh! Salvage!" But man, that thing just looked IMPOSING.
2. The designers want to reward you for picking a mech and sticking with it -- you will gain experience and become better at piloting your chosen mech, and that will translate into better accuracy and damage with weapon systems. This way, a player could specialize in a light mech throughout the entire game if they choose. < This. THIS so hard. Don't get me wrong, I loved stomping around in Madcats or Sunders or whatever big, bad clan heavies/assaults I could grab, but there was just so much fun to be had running around in a light mech, vaulting over people with your jumpjets and kneecapping them with your lasers. But in just about every game in the franchise, it stopped being a viable tactic as time went on. You -had- to armor up and start taking the heavier chassis because as nimble as you were, you'd still get hit eventually, and when you did, you were dead.
3. as well as support for a four-player co-op campaign < W-wargasm. Oh... oh, I think I just made a mess.
Oh... oh, wow. Ok, yes. I know this statement is rife with innuendo, but I'm totally willing to join a GOG lance.
4. I imagine this level of pretty may just kill my graphics card, though. Goshdarnit. :(