To preface this I think I'm best to share my system specifications:

• MSI GTX 1080 8GB
• Intel Core i7 7770k
• 16GB Corsair DDR4 RAM
• Samsung EVO SSD
• MSI H270 Motherboard

I have experienced many problems since I've participated in the Preorder Beta 2. Mostly performance based, as that seems to be the current complaint trend. I am fortunate enough to have a powerful computer, and therefore it pains me to even think about trying to play the game on another system. I sit on the highest settings (Void Anti-Aliasing and Shadow detail) at 1920x1080 and easily push above 80fps, which seems quite pathetic, as far as this game is concerned. Besides the random stuttering and low frame rates depending on what I believe is corpses(?) causing the issues with fps, the texture streaming is rather obnoxious, it feels like I'm playing RAGE. This is especially noticeable whilst spectating, changing from player to player drains all detail and takes a while to load in, even on my substantially good computer.
Textures in general have a bad time loading in, most notably the character models (of which are absolutely goofy (I'll come to that soon)) which are missing limbs, weapons, attachments, and other things that are common issues for character previews. I haven't experienced people popping in and out, but other players have witnessed this issue. Some textures, especially the Holographic Sight textures are atrocious and really hard to see past, making aiming much more difficult than it should be. high transparency should fix this, as this happens throughout all dot-related sights.
Character models and customisation, geez you have taken a step backward. Insurgency boasted really well textured character models and voices to go along with them, and Sandstorm seems to have forgotten about all of these excellent models and traded them for goofy-looking ones that actually look that out of place that it's a flat-out advantage to spot people. The customisation choices are piss-poor and are generally quite crappy, considering the actual variety in clothing in the real world. Especially military related clothing. A lot of the accessories look pathetic and out of place, making characters look even worse than they ought to be in such a great sequel.
Progression also seems to be bugged. I often don't receive XP when I perform well in a match, and then randomly receive a bunch of XP for achieving nothing. I'm not sure if Co-Op matches aren't supposed to give XP, but they do, sometimes.
Don't let the plethora of issues dishearten the devs, though, this truly is a great game, unfortunately though some issues really need to be rectified before the full release in 18 days. The gunplay and general gameplay is really awesome, it's exactly what I had expected when I heard of a sequel to Insurgency.