Any risk it will turn me into some sort of secret military super cyborg?

Seriously at this point I'd consider letting a werewolf or vampire bite me, if it would fix the damned Parkinson's.

Not a zombie. I already have the shuffling gait and long drawn out moaning...

I know of a Parkinson patient who developed an infection along the wires outside the brain. They removed the infected connection wires and he was good to go. He is a staunch advocate of DBS and would do it all again. Another was able to reduced his Corbadopa/Levidopa intake by 50%. Another had no change in medication uptake. What I've interpreted from the people I know and trust is that once again everyone is different and the changes will all be different for everyone. You just have to balance the risk vs. the potential reward.

Cognitively it's hard to say but that was definitely an issue at the end

Yikes, lots of thoughts on dbs
My brother had one, alot less medication and GOOD 7 years

I got a DBS and had to do 4 hrs of cognitive testing before they'd do the procedure