The Fear Ward change, like I mentioned in my last post, is primarily a convenience change for PvE. Reupping Fear Ward every 3 minutes when you need to keep putting Shadowform back on afterwards is annoying, and a large mana drain over long encounters. However, it wasn't crippling, so not a very big deal. What this will help the most is PvP, especially arenas. Having an arena match last longer than three minutes isn't unlikely, so you will probably want to put Fear Ward back up at some point throughout the match. Being required to drop Shadowform to do it is sort of a pain, considering both the loss of damage and the mitigation Shadowform supplies you with, arguably one of the Shadow Priest's strongest defenses.
The Spell Haste change is what has me a little excited. I'll admit right away, I haven't crunched any numbers. I'm notoriously bad at breaking down raw stats, I usually just eyeball my gear and take a guess. I'm right or pretty close more often than not but don't hate me too much if my guesses here are completely wrong. If you want to see some raw numbers, you can probably check them out over at the ShadowPriest.com forum.
I've noticed that in Hyjal and Black Temple, a Shadow Priest's damage starts to plateau. Through Karazhan, then most of SSC and TK, a Shadow Priest keeps pace very well with the other DPS classes. Every piece of gear is a substantial DPS boost, and there's little competition because Shadow Priests and Affliction Warlocks go for different gear than the Destro Locks and the Mages do. Things are pretty good! When Hyjal and BT come around, the iLevel system gets a little wonky. Because of how it works, the items that are split into multiple stats(crit, damage, haste) will eventually have a far greater overall DPS bonus than items that stack one stat: Spell damage. This becomes an issue when the Shadow Priests end up going after the "mage gear" because it gives us a better benefit than the gear "for us."
In the past, Shadow Priests have debated like crazy how useful Spell Haste really is for us, and there's never been a definitive answer. Some say yes, some say no, most say that its useful but only so much of it. Since Shadow spells are mostly instant or 1.5 second casts, Spell Haste only had an effect on Mind Flay, so it didn't make a very large difference. Now that the GCD will be going down with haste as well, it suddenly became much more desirable and I hope to see some great new Shadow Priest itemization in the Sunwell Plateau.