Well, Zerg is backwards, easy to kill for the first 6-7 minutes (if you all in), and after that, you're in deep shit, because once Zerg has 3 bases, their macro spirals out of control and they start covering the map in creep.
And yeah Reaper told me that SC1 was supposed to be a Warhammer game, but GW wouldn't give Blizz the licensing... GW is probably still dreading that decision.
Well... When you are trying to keep many many units alive at once, it becomes macro... Which I tell you, I'm awful at, I totally fail with Zerg every time I play them, timing the Queen's Larvae at each base, managing Overlords, and Units, becomes a huge pain in the ass for me.
That's the part I don't like about RTS games... Massive armies, 12 production buildings... Etc. Then it just comes down to like a WWII scenario, whoever makes more shit wins, and has nothing to do with casualty rates, which is where I specialize.
Zerg really bones every way you go... If you don't fast expand (90% of Zerg players do) you have enough reserves and a high enough production speed, to annihilate anyone you 1v1 in a rush, and if they fast expand, you will probably just wreck them... Now if you FE, and they don't, and they rush you, Zerg's production speed is so high, that you can counter immediately without even having units when he rushes you... Because this unit called the Queen, can drop larvae in a Hatchery, so instead of 6 Zerglings in 20 seconds, you have more like 12.
The only positive of a ZvP match for me is, one Zealot can tank around 3 Zerglings... And when upgraded, about 6. Problem is Roaches demolish Zealots, and their T2 counter-parts Stalkers.