I suppose this is meant to be a terrain template.
You should remove the trigger in that case.
The raw terrain itself (tileset, wireframe) looks all right, but you shouldn't spam doodads like this.
You've done this quite a lot, looks like some sort of terrainer laziness (because creating loads of different doodads to create a more realistic atmosphere takes quite some time).
Also, not everything fits together: the right side of the map (the shroom-trees with the leaves and blight) just doesn't blend in with the rest.
Another downside is the blizzard cliff'ed water. Water should (nearly) always be done with the raise/lower tool.
The difference is really enormous.
The entire down-right side suffers heavily from this. The drawback is that you cannot fix this the easy way: you must redo the entire map in order to use water like that (next time you start a map, please remember this! Always set the initial water level to shallow!).
Since this is only a brief overview (and I surely haven't pointed out all flaws), I'll check out the posts of other users first =D