The multiplayer is a bit buggy. The connected client often has problems like being unable to use ammo boxes. Happens to me frequently. Makes Boss fights stupidly hard. There are other bugs like infinite ammo bugs, and infinite stamina bugs.Host health potions heal over time, but client potions heal instantly.
Having said that, as far a launch day problems, these are minor. Play is smooth, responsive, if a bit arcade-like. Finding and connecting to people is easy, and setting to "Friends only" on steam is pretty great if you want to play alone or with select people.
Graphically good. I was dismayed at first, but realized the default settings were "Medium" once set to best the game looks and runs just as smooth. Well worth the $40 USD.