For some people, this change is a bit of a mixed bag. There is a lot of rumbling that Starfall is not a good choice in order to up balance's burst PvP damage. To a point, that crowd is correct. Starfall is not directly burst damage in the sense that Lava Burst or Conflagrate are, but it is one of the few burst capabilities that a balance druid holds. Starfall does deal a significant amount of damage, even in a PvP environment, however that damage is spread out over 10 seconds. That being said, it can also be used in conjunction with other abilities such as Force of Nature, an Eclipse proc, or even just free casting. All of that combined holds a very high damage potential. While the ability for Starfall to hit two targets for the full amount of damage is often brushed off by most Arena players, it should not be so easily ignored. Starfall can easily amount to around 10,000 damage to a single target, if the secondary target is not passively healed, it sets them up for an easy switch. Couple Starfall with the damage out-put of a well timed Lava Burst or some rolling shadow priest DoTs, especially during a Heroism, and you are putting out some very heavy damage. Balance druids may not have their own instant-15,000 damage i-win button, but they are very, very good at assisting other players in setting up their burst and being that tasty icing on the cake. It's a role we play exceptionally well at in Arena PvP, and this buff does actually help in that situation.
It took some time, but just this morning Ghostcrawler gave us what should be some solid numbers on how this change effects Starfall's damage. Originally, he quoted the current coefficient at 21%, while we understand it to be 4.8%. It was just a minor disconnect, but since it was so grossly different, it left us unable to calculate how this changes Starfall's damage. Now Ghostcrawler is showing that the coefficient will be 37% per star. This is a very major buff. Just to toss out some numbers, say you have 3,000 spell power, which is about normal for PvP and low for PvE:
(456 + 4.6% * 3000)*1.04(MSS)*1.06(E&M Personal) = 654.8256 per star
(608 + 37% * 3000) * 1.04(MSS)*1.06(E%M Personal) = 1,726.3584 per star
As I said, that is a very major change. With a maximum of ten stars per target, that is going from 6,548 damage to a single target to 17,263 damage to a single target. Considering that Starfall can hit two targets for maximum damage, the total damage of Starfall would be around 34,526. Even split perfectly 3 ways, that is a lot of damage going out, especially when you consider that you can still cast additional spells while Starfall is active.
The second change is a bit more...interesting. Nature's Grasp has been changed to now have three charges per cast, with a short internal cooldown between procs. Being the blessed creatures that we are, Ghostcrawler also spoke on this topic, saying this:
Nature's Grasp is a self buff that causes things that hit you to become rooted. That effect now has 3 charges. There is a small internal cooldown in between roots to keep say a rogue who hits you twice very quickly from wasting two charges. In your example, both the DK and pet should get rooted. If the DK breaks the roots and gets on you again, they will get rooted again (subject to the 45 sec duration).
The intent of this spell was to be a defensive tool for druids. Since it hasn't quite kept up, we wanted to try to get it to be more useful (i.e. do its job) rather than come up with an entirely new mechanic.
This change is very interesting, and, if I may say so, very awesome. There is still some testing to be done of the full extent of the new mechanic - such as how it shares diminishing returns with Entangling Roots (though the running assumption is that it shares a full DR) and if Nature's Grasp procs will cancel out casted Entangling Roots or even break upon casting Entangling Roots. All that considered, this should go a nice ways in helping balance druids escape from melee. Although Entangling Roots has not been taken kindly to due to the numerous issues that players have had with the spell, at least this change makes Nature's Grasp useful during those times where it procs only to have the druid instantly stunned into place.
Will these be the changes that push balance druids into the mainstream of Arena PvP? Doubtful, but they are most certainly a nice step in the right direction. Balance has always been a more difficult PvP spec to play successful as, but Blizzard knows we are out there, and they are going to be making the changes we need to become more welcomed in PvP. It may not happen this patch, but the day is coming.