I'm sure many people have issued their feedback for the game, both on this forum and through Steam's various platforms.
Let me start by saying I've been playing Insurgency since it was a Source mod. I enjoy this game a lot, it's a fun take on arcade shooters. I bought the standalone as soon as I realised it was available, and I even went and purchased Day of Infamy on sale. In general, I love these games and the gun play is always satisfying.
I can't overstate enough how much I hate artillery and kill-streak-esque helicopters in my infantry game. Battlefield 4, so far, is the only exception I'm aware of that really balances out vehicles in a primarily infantry dominant game, but even then I try my damndest to stay away from vehicles. But artillery to make up for bad map design is my biggest gripe about Day of Infamy, and it's my biggest gripe about Sandstorm. I only bought this game because of the competitive mode that I discovered after this free weekend.
Remove Commander mechanics, or make a Push and Skirmish mode without them; chemical warfare is the stupidest thing for a game that revolves around such involved gun play.
Fix sliding so that momentum doesn't magically bend me around things; if I hit an object, I should either move the object or stop moving myself.
You know about the radio bug, fix it.
There's an occasional bug that makes it impossible to choose a class in competitive on round start.
One time I got kicked for a Steam auth. error; I rejoined, played the whole match (and won) then received a thirty minute ban; make sure that can't happen in the future.
Is there a reason we don't have hollow points and armor piercing rounds anymore? I miss that.
Bring back Panj, Station, and Market; in general try and make more urban areas; I really detest the new maps outside of their competitive Firefight mode.
Bring back Ambush.
All in all it's alright. I wish I had a better computer and the game was better optimized so I could get more out of Push or Skirmish, but the competitive matchmaking is pretty entertaining as it is. I still think the standalone is much better, but that might just be the flexibility of Source and its user-friendly aspects (the developer console is a godsend I miss in Sandstorm). There have been awesome improvements like letting me change IFF colors, but I miss having a dedicated map button. Definitely worth the 22 ish bucks after tax I paid for it.
I do wish y'all would go back toward the original Insurgency though.
Also, if y'all have time, you should work with the creators of E.Y.E. Divine Cybermancy and make a sequel to that; that would be fucking mind blowing I bet.