I've just ran around your map and I got this:
The map has no health-ammo kits, you should place them right away.
The spawnrooms feel kinda small
You should

every stair in your map, so you don't get the 'hop' effect when you go up them
This spot looks rather empty. Maybe placing a platform there will make it look more interesting... Like this:
dat ms paint skillz
What is that prop doing there?
The soldier also looks dark, maybe put more light down there?
Displacement seams! Be careful with those. Not a big deal though.
Those brushes have the wrong team color on them. Still not a big problem, but it doesn't look ok.
Another empty spot... Hey! another seam!
And that happens with the snow storm particles when I'm inside the buildings near the point. I have no idea how to fix them or if it can be fixed, but it's not annoying so don't mind doing something about it yet.
Finally, I really liked the snow storm. Later you can add some fog to make it look cooler
crap, i've made a pun.
And the skybox... I don't think it's the best one for a snow storm, maybe you can use sky_stormfront_01 instead
EDIT: The sniper model is also dark, like pic 4