The rogue must be able to see the target well enough
to pick out a vital spot and must be able to reach such a
spot. A rogue cannot sneak attack while striking a creature
with concealment or striking the limbs of a creature whose
vitals are beyond reach.
Can we get rid of this 3.5 inheritance? At least the part about concealment? The bad thing about it is that rogues should be masters of combat in shadowy conditions. Now, they're not - dim lightning gives a miss chance, and that kills off Sneak Attack.