I have no idea how to play Injustice 2, a fighting game featuring characters from the DC Comics universe, but after some embarrassing rounds in the free beta I have largely positive impressions of the fighter. Barring any yet-to-be-discovered performance issues with hardware I haven't tested, this appears to be a good PC version.
Like most fighting games, the framerate is locked at 60, and in online play frame skipping is automatically enabled, meaning that frames will be dropped to maintain 60 fps so that both players are seeing the correct timing on animations. It also includes the option for dynamic resolution scaling—meaning that it will automatically drop the rendering resolution to maintain the framerate—though I didn't need to turn it on.
During fights I didn't notice any frame skipping with max settings at 2560x1080 (yep, it supports ultrawide aspect ratios). This is with a Core i7-6700K @ 4Ghz, a GTX 980, and 16 GB RAM.
The built-in benchmarking tool does a pretty good job of determining if your PC and settings are ready to go, though in all cases, whether at 1024x768 or 2560x1080, my average fps was 59 and my minimum was below 50. That's due to a framerate dip that occurs at the very beginning of the benchmark, and also in-game, just before a fight starts. But by the time control is turned over to the players, it always ramps up to a solid 60 fps, so just look for the benchmark to maintain 60 fps from the start of the fight onward.
If you don't want to tinker, Injustice 2 includes the option to automatically apply settings appropriate to your hardware. For me, all it did was turn texture quality from 'very high' to 'high,' but I didn't have any framerate issues at 'very high.' I'd suggest running the benchmark at max settings to see if you really need to reduce anything.
My main performance complaint is that the pre-fight menus are sluggish, especially the character select screen. There's also my performance, which has been very bad (two wins, many losses). The beta is not a great way to get accustomed to Injustice 2. There's no practice mode—only online matches—so there's no way to look up moves except while being pummeled in a match or on the web. I understand that it's a technical beta, but it'll also be a lot of players' first experience with Injustice 2, so letting us get dunked on by experienced Xbox players with no option to practice might've been a poor choice.
I do like that Injustice 2 shows you who you've matched with, their win/loss count, and your ping before the fight is confirmed, giving you a chance to decline if you feel it's a poor match. Ultimately, it'll mean nothing if you're repeatedly matched with distant or superior players, but the transparency is appreciated. I've been running into fewer experienced players as I continue testing, presumably because they've racked up some wins at this point (and I haven't).
My best experience was matching with a friendly guy who called a truce so we could learn our moves. Just be warned that voice chat seems to be on by default, and I haven't found a way to turn it off. I hope that's fixed before launch, otherwise you'll have to manually mute your mic if you don't want to broadcast to your opponent.
I haven't encountered noticeable lag, so after several hours with Injustice 2, I'm just about convinced that it could release as-is and I'd have few complaints. Of course, there may be hardware I haven't tested that struggles with it, or drivers that cause issues—we'll have to see how AMD cards fare especially. If you've tried it out, let us know your specs and benchmark results in the comments. The best thing about demos and free betas is that you get to test performance before buying anything, and you have a few days to do so, as the Injustice 2 beta is running through November 10.
The full game is releasing on Steam and the Microsoft Store on November 14, just a little over a week from now. Hopefully that's enough time to improve the menus and add the option to disable voice chat.