It looks like the changes are targeted to hurt his lane a bit. But I don't think it will be noticeable enough.
3% health won't be too much of a difference during laning phase since his health will still be relatively low.
The mana change might make a bit of a difference, but I'm not expecting much. I'll have to see it.
Honestly I just think it should be more punishing for him to miss his Q. His identity has always been lane bully. But they want to make him into somebody who can do that and also scale into a rolling locomotive in late game. Which would be ok, if it wasn't so damn safe to be Darius right now.
I think you should be rewarded more for baiting it out of him. He should be punished more for missing it. Maybe a some mana refund on hit at a higher total mana cost. Or just a flat higher mana cost. Or perhaps a higher cooldown, but compensation so it's more potent when it lands. Just thoughts