Seriously?! Yeah!! Slotted are a shit load better than just standard.
Improved stopping distance, improved feel, etc. I even went from a cross-drilled set to a slotted set and noticed a huge difference.
They improve braking power, basically. That and a good set of pads!
Most properly modded street cars, you'll find with slotted rotors. As well as all the HSV's and FPV's that came out the factory, and a few BMW's.