From what I read, the PTR AoV does the same thing Live AoV does right now, with two changes:
1). You do less damage per attack.
2). You gain 3% mana regen every 1 second. (not sure if this is while casting, or no. Probably not while casting).
What this does, is fill your mana up even faster than it did before, AND, you can refill while not even in combat, which is nice. Sometimes I'm walking towards my next mob, and I wish I could fill up. Or I'm about ready to pull an elite and I'm not full MP and I don't feel like waiting for my measly 15-ish mp5 to heal 200-some MP.
So, with AoV, 33 seconds will fill your mana from 0 to 100 without firing a single shot. I rather like that. That's very close to what a bottle of water does, really. So basically, no more drinking water, and you can shoot mobs to get it back even faster.
A very nice change.