Here's what Zerg looks to me (and many others) now:
a. Boring. Roaches, an early powerful unit that absolutely needs to be pushed out, kills everything it faces and all the fun with it. The role of Zerglings has been downgraded significantly.
b. Not challenging at all for Zerg user. The Zerg units setup in StarCraft II reminds me of an early version of StarCraft, pre Brood War. Let's say in StarCraft 1.04 there were no medics, lurkers, corsairs, no muta micro either. Hydralisks were 75 minerals only, later added + 25 gas, they were slower, had shorter attack range (sounds familiar, doesn't it?). Also there was no variation, only unit at Tier 2 was Mutalisk, and it was just as useful as Muta can be without Micro.
c. Zerg is now very similar to Protoss in SCBW. It has a strong early unit/combination, like never before. It can easliy live off and produce tons of units with 2 bases, there is no real need to go to Hive Tech, because there're no defilers and new Guardians or whatever they're called just suck.
As a result of all that I believe Zerg needs to be retooled.
1. Baneling Nest should be an upgrade for Pool available on Lair Tech, as a trade-off banes should be made more powerful overall and especially against protoss, maybe 120% damage on shields.
2. Remove 'underground movement' ability from roaches, immense healing speed while burrowed is more than enough.
3. Add a mutation or an upgrade for roach that would make it easier to stop early Protoss immortal push, it needs stopping power, not offensive power. Roach as a unit should not be able to win all matchups, like it does now. Perhaps a +defense or +something on your own creep will do for better defense and give an opportunity to fiddle with roaches on extra dumped creep later in the game.
4. Bring back lurkers or a variation of Hydralisk mutation to create a level 2.5 tech, capable of moving while burrowed. (AFAIK Lurkers were removed just before Beta, i played Lurkers in a build Blizzard brought to Russian gaming expo, Roaches were weaker though)
5. Mutalisks to compensate for the lost micro need some sort of an extra third upgrade (researchable) extending the range a tiny bit or even better - the amount of consecutively hit targets by whatever they attack with.
6. Zerg needs a better caster unit on 2nd tier, maybe bring back Plague capable of damaging only to 50% or the same plage but lasting half as long, maybe even slowing regeneration/healing rate, but keep mind control ability as a trade for Swarm.
7. Lings need to be a little tougher, maybe at the expense of decreased speed with glands researched.
8. Because for whatever reason Zerg is now way slower and uncomfortable switching tech in comparison to BW, maybe it's worth adding a way to decrease Lair/Hive building time at a certain extra cost.
I submitted those to Blizzard, not that they would listen to a C+ (at best) noob, but still.
P.S. If any TL admin or editor would fix the title to Tweaking, that would be very appreciated. Thx in advance.