Your level looks completely different in-game than it does in Hammer. Only very recently did it even get a lighting preview; Before you didn't even have any idea how lighting lookedThis is bad.
The interface is almost audibly clunky. Scroll bars to move the views, really?Space + click & move mouse = pan
It's completely axis-aligned. Making anything other than rectangular geometry aligned to the grid is an absolute nightmare. E.g. you can't make a building rotated 45 degrees easily. You can't make a wall oriented 45 degrees to the grid a certain length, unless you first make it aligned to the grid and then rotate itAs annoying as this can be, there are ways around it.
It's based on brushes, even though it compiles into into non-brush geometry. So if you just want say a single face, you have to make a brush and texture the other 5 sides with a "nodraw" texture or some such bullshitThere is a tool to separate a solid into its vertices. I don't remember what it was called, though. (And I'm not talking about the displacement tool, either. It was something else.)
There are almost no tools for anything other than blocks. God forbid if you want to construct complex geometry like archways, curves, tunnels and stuffCube + horizontally rotated cylinder/sphere/torus + carve = archway/tunnel/curve/what have you. There is an archway primitive, but it sucks.
The I/O system is ugly. There are no visual links between anything; If one entity outputs to another the only way to see is to open one's properties and lookA minor annoyance to me, at least. I'm just happy when my triggers actually work :/
There's no UV wrapping! Aligning textures is a bitch, especially rotating them (again with the axis alignment)I don't know of a way to rotate textures, but the "Toggle texture application" window has plenty of UV workings, just named scale X/Y and offset X/Y, which I am typically content with.
You have to compile to test anything. Now, there can be real, valid reasons for that but in this day and age it's just not acceptable. Find a different solution that allows you to instantly and immediately test something. Murder the frame rate, that's fine. Just let me see how the damn thing looks without waiting for 5 minutes for the thing to compileIt usually takes about 30 seconds unless you've added a lot of new lighting since the last time you built it. Even then, there are options to do faster (but less pretty) compilations if you want. It's annoying, but patience is a virtue.
Madk, let me help you make maps somehow.

I'm still wrapping my head around why my spawn-event triggers won't work, but if you want to give me some sort of level design, I can run with it. But note:
Keep movement southward to an absolute minimum
Keep movement eastward/westward from being too much
Crammed spaces are bad
No two-story buildings or w/e