So... I have had my hands deep in the Starcraft 2 Beta for about a week or so now, getting familiar with my favorite race from Starcraft Classic, the nightmarish Zerg. Impressions below!
Zergling - This unit has gone from the staple of the race, even terming itself into gaming jargon, to absolute crap. In my 100-ish matches played, I have only seen them used effectively once. The cost of 50 minerals for 2 units isn't bad, but they don't stand up to Zealots or Marines at all. This unit went from being a early game threat to cannon fodder. And once the higher units start to pour out; Hellions, Marauders, Stalkers and Immortals, the zergling falls before it can do anything. The speed upgrade and massive numbers might prove to be effective occasionally, but the resources are better spent else where.
Baneling - The evolved strain of the Zergling, Banelings make great at taking down bunched together troops and buildings. The downside? You have to build an entirely separate building to give your Zerglings the ability to change into Banelings. This makes the unit feel like an after thought, as they become irrelevant late game when melee units are useless and they get gunned down by ranged to fast to do anything. Maybe a buff with a small increase to armor would make this unit more appealing, but as it stands right now, I would rather invest in building a Roach Warren than a Baneling's nest.
Roach - The new go to tier 1 unit. A strong but slow ranged attack helps, but the magical number for this one? The 2 armor it starts with right out of the gate is the key to it's success (And I am sure the key to it's eventual nerf). Add on the strong attack that is devastating under the effects of focus fire and you have a strong unit that holds its ground until the flying units show. For some reason the roach is unable to tilt 45 degrees and attack upward. Good for early game strength and with the ability to burrow underground and move, research pending, this unit has become the replacement for the worthless Zergling.
Hydralisk - In Classic Starcraft, this was the best tier one unit in the game, hands down. It had a strong ranged attack and they worked great in numbers. Coupled with the Defilers (RIP) Dark Swarm ability, they were a force to be reckoned with, even against some heavy air hitters such as the Carrier and the Battlecrusier. They even had some defensive maneuverability with the ability to turn into Lurkers, the burrowing mobile equivalent of a tower. Well... the Starcraft 2 Hydralisk is a bit of a mixed bag. Moved from a tier 1 unit to a strong tier 2 unit, but losing the ability to transform into a Lurker, the Hydralisk still hits hard and fast, but doesn't play well with other units due to it's un-increased health pool. They work great in large numbers but still fall one on one.
Infestor - Under the right circumstances the Infestor can be brutal. Turning ones units against them for a brief 10 seconds can turn the tide of battle if the unit is picked correctly. This ability is useless against lower tiered units, but great against something stronger like the Immortals, Siege Tanks, and Colossus. With the ability to move while burrowed, this allows for pop and run tactics to keep the enemy guessing. A support unit that defines support, this unit is useless on it's own, but can be quite useful on a large scale battle.
Mutalisk - The staple flying unit of the Zerg, now massed quicker than ever when coupled with the queen's ability to spawn larva at an alarming rate. Their organic armor gets ripped to shreds pretty quickly, but the numbers you can put out outweigh that small disadvantage. Great against ground units do to the bounce attack from the acid spores it fires, the Mutalisk is a good counter against Immortals and Marauders, but for some reason can't hold a candle to Stalkers. Once things become a strictly air affair, the Mutalisk folds pretty quickly, specifically under quick focus fire, but they are great for harassing ground units.
Corruptor - The new Zerg anti-air unit, the Corruptor pairs well with strong Roach support, as their attack speed seems about the same. Focus fire is the key to using this unit effectively against late game heavy air such as Battlecruisers, Carriers, or the feared Mothership, and the ability to spawn into Brood Lords makes their ground cover pretty strong too.
Brood Lord - Sadly, not the feared Gaurdian that the Zerg had in Starcraft Classic, the Brood Lord attacks by shooting broodlings at it's targets, giving you extra units on the battlefield. Good for supporting an already on going battle, but horrible for staging an assault. The Corruptor fares better in air-to-air combat, so the Brood Lord is more situational than anything. Horrible as a defensive unit, fighting a Colossus comes to mind, this unit is best served as a Corruptor instead.
Ultralisk - The one Zerg unit that makes an opponent piss their pants, and with good reason. The Ultralisk can make quick work of most ground units. However the Ultralisk is EXTREMELY vulnerable to air attacks and is useless against air units. The heavy cost of the unit would be better spent on a mixture of Hydralisks and Corruptors honestly, but the Ultralisk is a solid bet when victory is already confirmed.
So what is the best way to use the Zerg in this brave new world? Well... sadly that answer hasn't changed from Starcraft Classic. A mixture of units seems to be the way to go, but in the world of Thor's and Motherships, we will see how the Zerg stack up in the long run.