Mission 1
Similarly to Unlikely Allies, another quick introductory mission. Good selection of available technologies, given the difficulty level you could probably disable level 3 upgrades. The layout is very linear (which isn't necessarily a bad thing) with good terrain all around. Nice triggers at work with the Nydus Canals and the refugees travelling to the Warp Gate through the fully revealed canyon. You should probably remove the High Templar in the last group, mainly because of his slow speed: he makes the final sequence a bit tedious, and he also constantly comes in the way of your units who are trying to escort the group of refugees. Just out of curiosity, I tried to kill him before he could reach the Warp Gate, and something very strange happened: I won and I was defeated at the same time! Unfortunately I didn't take a screenshot, however this is what happened: the message "A Khalai has been killed" appeared, along with the victory message (with the units still moving in the background). The victory screen followed, but then the same map was reloaded as if I was defeated. When these things happen, it's usually a conflict between two or more triggers, and probably it's just a matter of timing. This problem does not occur when other Purple Protoss are killed, only with the last Dark Templar (one more reason to get rid of him, I guess).
I also suggest you to remove or reposition this rock pillar, since it causes some pathfinding issues in proximity of the ramp:
Mission 2
I love defense missions and I'm always excited when I stumble upon one of them. This being said, there are some issues with this map. The main problem is the way the mission was conceived: the map is just too big, and there is an additional resource node that goes almost unnoticed and that nobody will probably claim, since the gameplay is aimed at turtling, not at exploring. The resources available in the starting base are scarce, but luckily the mission can still be won without expanding. As a consequence of the double personality of this map, the tech tree feels too generous, with several advanced structures that are just too expensive and will serve no real purpose if built (like the Observatory, and even the Stargate, since the player will receive Corsairs at some point). The layout and terrain are good, but then again, most of the map will remain shrouded in the fog of war for most players, which is a shame. Of course I don't expect you to remake the map on a smaller scale, but there are some things you can do to better adapt it to the intended gameplay: maybe you could increase a bit the starting resources, or create a more accessible expansion, or restrict the tech tree, or increase the duration of the mission so to actually encourage the player to expand - there are many possibilities.
Another problem is related to the stated objectives vs the actual defeat conditions: I was a bit surprised when I lost because a Mutalisk reached the Warp Gate, since the objective simply stated "hold off the Zerg". While the actual defeat condition does perfectly make sense, you should probably highlight it in the objectives, something like "Let no Zerg slip through the Warp Gate" or similar.
As for the attack waves, they are well balanced in the current game state, however you will likely need to tweak them a bit if you are going to do some of the gameplay changes I suggested above. I really liked the reinforcements coming from Shakuras, they came as a nice surprise during a tense moment, and proved to be useful throughout the whole mission.
Mission 3
I ran into several problems when playing this mission, I will briefly summarize them below:
- The Infested Terran trap is extremely unfair. The player gets almost no time to defend against it, despite being hinted of the danger by the Infested Command Center. It took me three attempts to properly place Spider Mines without losing Raynor in the process. I don't know if there are other ways to survive this attack (maybe by using the Zealots as cannon fodders?)
- I think that the player should lose if all of his Probes are destroyed before he can establish a Nexus: during one of my failed attempts at killing the Infested Terrans I accidentally lost all of my Probes, and there was no more way to win the mission.
- Waiting for the creep to recede was an ordeal, further accentuated by the low starting resources. You definitely need to do something about this, as it may draw major criticism to your map. I strongly suggest you to remove the Creep Colonies, I know that creep looks nice there, but your map will greatly benefit from a faster start. If you really want a bit of creep in your base, use a single Creep Colony or an Hatchery, so the creep will recede faster, and put it as far as possible from the minerals, so the ground will become buildable in a reasonable amount of time. Your new infested base may look something like this:

- The resources were really too scarce, both in the starting amount and in the available mineral fields: a Defiler managed to cast Plague over my units before I could set up an expansion and I was basically bankrupt.
- Out of frustration for having not enough resources, I managed to sneak three Shuttles (one with Raynor, the other two as decoys) past a relatively unguarded spot, however the triggers failed to work: when I brought my Shuttle containing Raynor to the Beacon, I took control of the Terran units, the new mission objectives appeared, but suddenly Raynor said "we arrived too late" and I was defeated.
- I don't know if this was intentional, but the Beacon you have used is actually a Flag Beacon, which automatically spawns a fancy Flag.
- The objective "The Raiders' base must survive" doesn't sound right to me, "The Raiders' base must not be destroyed" is more correct, in my opinion.