I've now played 6 games of 8th edition (2 wins against guard, 2 losses against Grey Knights, one win against Dark Angles and a win against an Alpha Legion list with 40 berserkers, so 4-0-2 so far) and I'm beginning to get the hang of it. Llike most people, I'm impressed. It's simple and streamlined, but still sufficiently complex to be entertaining. The only thing I miss are vehicle facings and firing arcs. Firing arcs in particular added more depth to the game, and helped to reign in flyers (which are of course way more powerful in 8th).
But overall, I'm loving it!