Netcode is broken and awful. I haven't played one smooth game so far. One game seemed smooth, but the opponent wasn't doing anything. I read reports that there are a lot of games where one person can move lag free while the other stutters.
They really need to just put GGPO or something else in there. The devs are the Steam forum saying, "We don't want to change the netcode, because some people are having great experiences." (paraphrase), while at the same time everywhere else on the Steam forum says, "Netcode is broken, FIX IT, ADD GGPO."
The game also has trouble recognizing some arcade sticks. Something to do with it only reading the analog pad inputs (not confirmed, but I think that's what's going on).
The offline game is great. I've been enjoying playing UM again. Good if you want to play it offline.
Update from the Steam forums (posted by a Code Mystics dev):
"Thanks to the amazing investigative work of Miggoh, we have a reason for the inconsistent netcode behaviour. It corroborates earlier reports that the problem would happen in matchmaking but not invites.
When you start matchmaking you get bombarded with matchmaking requests and it's not shut off. Those are hogging your bandwidth, which is what's driving up the ping to ridiculous numbers. The reason we didn't see this prior to shipping is that we didn't have 1000s of people playing the game...
We'll be singing your praises to SNK for the Steam community's help in sussing out some of the major launch bugs so quickly. Your input will help us get you updates so much faster. Thanks everyone!"
Once they patch it, I'll try it again. It's great they have some communication.
Not entirely, I had days off left to use, but KOF98UMFE was supposed to be a nice bonus.