The changes to Chariots is pretty big in my opinion. There is even a sentence using Necrons as an example for using Reanimation Protocols for the rider of a chariot. Never being able to disembark, not gaining an armor save bonus, overall the rules work better for a melee oriented attack using the Necron special sweep attacks and gives more of a reason to remove wounds from the Overlord instead of taking vehicle damage. *edit- was this FAQ'ed out then? What a bummer, but probably moot because the Chariot's owner gets to allocate wounds between the vehicle and the rider*
I'm still piecing my way through the rule book checking up on Necron specific stuff but so far this is really the only change that effects my play style so far. I might need to fork over the extra points to give this Overlord a Sempiternal Weave now.