Ok, I think UMvC3 netcode is much better than MvC3. Thing is I believe player matches for some reason lags more than ranked matches. If someone else can confirm this, please.
As for impressions of the overall game and characters.
They seemed to have nerfed several characters that really didn't need nerfs and buffed certain ones that really didn't need nerfs.
Tron - nerfed to hell, even as point character. Can't really combo off air H that crosses up, which is pretty much her only real way to get in. You're going to need some sort of beam assist to help with this.
Zero - He feels different, can't do certain combos, like the j.m, j.m, j.h loops. Also, juggling after a f+H is difficult and spotty at best outside of the corner. Even though he now has the ability to cancel into buster from his special moves, overall, I think he got nerfed.
Spiderman - Great character, the ability to go web zip after specials is great for pressure (safe btw, can block after web zip). Although the web throw was nerfed, spiderman can rely on just ultimate web throw resets or his other hyper which do plenty of damage.
Doom - j.S, nuff said. He's pretty much the same guy, except with better tools.
Morrigan - She still sucks. I don't know what the point of this character is besides trying to abuse her meter gain assist. As for the air dash nerf, I don't think it's that bad. All Morrigan players need to do is go into flight mode and air dash from there so they can unfly when needed. Her damage is still ass.
Deadpool - he's pretty much the same, but the teleport from guns is a safe way to get in and out. He does average damage still, but his keepaway remains solid.
Ryu - Haven't been able to play him that much, but he's definitely better. Being able to cancel overhead into launcher or special will save the x factor or need for assist. Still does awesome damage off basic stuff.
Iron Man - Ass, nuff said. Air dash is pure ass.
C.Viper - The same, she's good, but it depends on execution and the player to deal some damage. The new optic laser is a great addition as it gives a sort of answer to long range keepaway.
Sentinaaall - Pretty much the same guy, except drones are faster which I think is a buff. As for rocket punch no longer comboing into hyper sodium force, all one needs to do is tk rocket punch into hard drive. Still a good character, but still squishy.
Wesker - Ok, I take back what I said about him being nerfed, this guy got buffed and is definitely one of the top tier, at least top 5, maybe top 3. 1mil is plenty of health still. His teleport mixups are intact. And now he is able to teleport off qcf+l making it safe and giving him position. Also his Hyper 1 got buffed. Now it doesn't just hit people, it powers him up (he takes off his glasses becoming faster and stronger). It's basically a powerup and attack hyper in one.
Those were the characters I really only played in Vanilla. But the one I'm really scared of is Dormammu, that guy is on steroids.
As for the new characters, I'm really only looking at Nemesis. He's pretty much a better Ghostrider/Hulk rolled into one. For the rest, the only ones that seem to stand out are Hawkeye (She Hulk/Taskmaster/Spencer in one) and lvl 4-5 Frank West (pretty much untouchable by then). Vergil, not so scared of, once people realize how to punish his everything (all his moves are unsafe), he won't be so scary. Strider does ass damage. Firebrand looks interesting.