this is about as "old school fan" (yobnaf can't be used apparently) as i get (which really isn't "that" bad honestly)

i'll get the first stink bug in the punchbowl out of the way.
3rd person: in short, i don't like it and don't think it should be there. however i don't think it "destroyed" the game and warranted the level of player riots it caused. i don't use it and it's bad yes, but i'll live.
Gauss Rifle: this one caught me by surprise, adding a timing "game" to fire a weapon that; in my opinion was just fine the way it was. will a: confuse new players, b: really annoy the older folks and c: i just totally stopped using a Gauss on any mech i had it on. it's already big, heavy and easy to break. i decided i didn't want to deal with "this" too.
Jump Jets: the initial jump jet shake, made me stop using my Jenner, the later change to reduce it, made me a little more able to use it again (modest thanks). i was really hoping the effect would get tossed in the scrap heap, but it looks like it's here to stay. i would have at least preferred the shake to be taken off at least the Lights, but i can still pull off pretty good jump shots in my Jenner if i tap the jets just right. so i'll cope.
Mech appearance: now this i liked. you change out equipment on a mech and you'll actually see the different stuff actually "on" your mech. i thought "neat!" right. although it seems that many of the previously released mechs got neglected. if i take the AC20 off my Atlas the gun is still there, if i change my Awesome it's set up still looks the same no matter what i put on it, among others. i'm not sure if there is any plan to update these later, but i hope there is.
Ghost Heat: i simultaneously both like and despise this one. i could say that we kinda brought this on ourselves by making boring yet effective loadouts (like cramming as many PPCs as you can on a Stalker). i do like that don't see that dam 6 PPC Stalker as much anymore, but i think the change should have been limited to the bigger weapons. in general the change didn't affect my play style that much. i almost always varied my weapon loads on my machines, hell my Atlas sports 2L lasers, 2M lasers, 2 LRM15s and an AC20. i run on chain fire to keep a constant stream of damage and that's i did before this change as well. it still works.
well those are my thoughts, i don't think they really "killed" the game... but it did receive a few stab wounds. with proper medical treatment it can recover with no permanent damage, but there may be some trauma and mental scarring.