This map is good for a first one you made. Though i got a couple of suggestions:
1. Terrain. Adding some doodads here and there would make the game look better.
2. Quests. Add some more of them.
3. More heroes to choose. This one is optional only, but im sure it would increase the variety of people playing, and it wouldnt look like Clone Wars.
4. More items. Examples: Armor(3 types), Predator Mask, some potion type items.(health and mana would be good) And i find the termo detector useless for now unless you gonna put some invisible units.
5. Better Aliens Variety. From what i seen youve put in 2 types of aliens to now.(excluidng the Queen) You could add a permamently invisible alien in the later part of the level so the termo detector will be useful.