I'd say that for the most part I am very pleased with the changes in 8th edition. Melee combat seems more decisive, shooting is a little more effective. Warmachines have been made worth thier points.
The only thing that I have a problem with is the % based list building. More specificly the fact that lord level heros may be taken in any sized games. The rest of the % based system is awesome but I feel it's game unbalancing when a player can take a lord level caster in a small points game. I just find it makes for lazy gaming/herohammer.