A grown-up brain in a CCU suffers a -1 dicepool penalty when using learned skills - through a drone or in the matrix.
If a fullflesh rigger uses the same skills through a drone or in the matrix, he doesn't suffer any penalties.

they also get a bonus to all vehicle skills iirc.

really, the main disadvantage to cyborgs is that they are so ridiculously overpriced for what they do, that it's basically never really worth it to make one.

I think the price reflects prototype cost right now. Once the tech is perfect, they just have to rip out your brain and put it in the yar - basic brain surgery, should cost as much as implanting rigger controls.

Well don't forget a couple things.

#1. "Cyborgs' don't really appear to be target at player characters just yet. The rather dramatic upkeep costs alone pretty much prevent it, not to mention the insanity rules.

#2. Not THAT many great drones bodies you can use yet. However a Steel Lynx, modified Step-Van or Citymaster (if you could get one) are all decentish.

#3. Raiting 5 skill wires! Why would you spend points on skills again?

#4. As a cloned brain you get +3 to pretty much every action in the physical plane! And autosofts could potentialy raise that even higher.

#5. You are flat out immune to all mana spells. And you are high resistant to most physical ones (need more than 4 successes to even begin to effect you).

#6. Hardened armor. If its modified power is less than your armor, ignore it.