Okay, so I might think that completely revamping the talent trees yet again is a really bad idea (I think Nils has a very good summary on the subject here), but that doesn't mean that I'm not curious about what new talents the developers are thinking of for my class. Let's have a look, shall we?
Tier 1 aka The Mass CC tier
You only need to take a brief look at the new system to see that every tier of talents seems to focus on a certain theme, such as survivability or crowd control. The first tier of priest talents appears to be designed around our mass crowd control, and sees Psychic Scream being turned from a baseline ability into a talent with alternative options.
The Good: I think that the three options given here, mass root vs. "fearing totem" vs. the old psychic scream are interesting alternatives to achieve a similar effect. Void Tendrils sounds like a good way of getting melee off your back in an environment where psychic scream frequently fails to achieve much because so many classes have been given counter-fear measures by now. (Though I noticed that they are also planning to give shamans an anti-snare totem in MoP. Clearly the class is meant to remain our nemesis in PvP.)
The idea of a fearing totem, which is what the Psyfiend basically sounds like, is a very funny one. It's nice to imagine dropping this on top of a flag carrier under pressure for example. I do suspect that it will need buffing though, because one single-target fear every two seconds for ten seconds is not that amazing, and most of the effect can still be nullified by a single tremor totem while it still has twice the cooldown of good old psychic scream.
The Bad: All the good things above refer to PvP only. In PvE this choice is likely to feel borderline pointless for all specs, because single target crowd control is already used rarely enough in group content, and mass CC is used even less. At best you can probably hope to get some use out of it if you get into a tight spot while questing, but I'm not sure how likely that is to happen anymore.
Tier 2 aka the Movement Tier
This one currently looks very boring to me unfortunately: increased movement speed after getting bubbled vs. increased movement speed while levitating vs. Fade removing movement impairing effects.
The Good: Body and Soul is a fun talent right now, and I guess it's nice that they are making it available to all specs - I miss it all the time on my shadow priest.
The Bad: As it stands, I don't see this tier offering any genuine choice. I just can't see anyone taking Path of the Devout. Body and Soul is the clear winner for PvE, because being able to get out of the fire sixty percent faster is amazing. And Phantasm will probably be the undisputed choice for PvP in the future, since snares are the bane of any priest's existence. The only reason it would lose out to Body and Soul right now is that the current PvP 4-piece bonus for priests has something similar baked in for whenever you shield yourself. Hopefully something will be done to make this entire tier less of a no-brainer.
Tier 3 aka... Shinies?
Aha! Finally something that affects the priest's actual role, whether it's healing or damage dealing. We get to pick between Surge of Light / occasional instant Mind Blasts that consume no shadow orbs, a shiny holy boomerang of healiness and Archangel with the mana regen aspect removed.
The Good: For healers, there's a genuine choice here between saving mana with Surge of Light or increasing your output with Archangel (assuming that all specs will get Evangelism as well, otherwise having this as a talent would be kind of pointless). Divine Star sounds like the kind of ability that might end up with an awesome spell effect that makes you squeal in delight every time you use it, though its usefulness remains to be seen.
The Bad: Shadow doesn't appear to have much of a choice here. Two of the three available talents give dps boosts, and it will probably only be a matter of time until theorycrafters figure out which one is better.
Tier 4 aka The Survival Tier
Another tier that I feel very meh about as a whole. From what I gather they intend to give all classes a pick of survival talents, but I feel that to a priest the whole concept is probably less exciting than it is to other classes. Shadow already has a good survival cooldown in Dispersion, and the two healing specs are already dedicated to guaranteeing their own survival with their default tools all the time. Anyway, the offerings are Desperate Prayer, +30% effectiveness for bubbles on yourself, or a bubble that gets auto-cast on you when you get low on health (once every 90 seconds).
The Good: I think there is an interesting trade-off between Desperate Prayer and Final Prayer. The former has a slightly longer cooldown and you have to actively cast it, but you can choose when to use it. The latter is applied automatically and occurs a bit more frequently, but you have no influence on it; it just happens when it happens. That sounds like an interesting choice in PvP.
The Bad: Unfortunately I suspect that Angelic Bulwark is always going to win out over both of the abilities mentioned above, since getting more absorption and thus protection against spell pushback from your shields all the time sounds like a lot more bang for your buck in almost any scenario I can imagine. Also, I don't like that Final Prayer sounds like they just copied over Sacred Shield from the paladins and increased its cooldown.
Tier 5 aka The More Damage and Heals Tier
Aha! Finally another tier that affects core abilities! In this one we have more damage and healing done to targets at or below 25% health, Power Infusion and Serendipity / a tweaked version of Mind Melt.
The Good: I reckon Power Infusion is one of those talents that every spec would be happy to be able to pick up. Disc priests might enjoy being able to grab Serendipity to boost their single target output even more when required.
The Bad: I thought that we were past the age of flat bonuses to damage and healing. I guess holy is going to be rebalanced either way, but at the moment I find it hard to even imagine functioning as a holy priest without Serendipity, which wouldn't leave me any choice but to take that. I think for shadow PvE Power Infusion is going to be a no-brainer; I don't know enough about its PvP side to be sure what a PvP-ing shadow priest would pick here.
Tier 6 aka The New OP Spells
This tier is exciting simply because everything in it is actually new, and a lot of it looks extremely powerful in its currently suggested implementation.
First we have Vow of Unity, which looks like it's inspired by Beacon of Light and Hand of Sacrifice. Then there's Void Shift, which swaps health percentage with a friendly target, and Vampiric Dominance, which applies free extra heals to three nearby friendlies every time you heal or do damage (though it doesn't say whether they have to be near you or near your target; I assume the latter).
The Good: Well, it all sounds very exciting, doesn't it? Void Shift would be another very powerful survival cooldown that can either be used on yourself or someone else. And Vampiric Dominance sounds amazingly powerful for a healer (kind of like the old Flash of Light glyph for paladins, except even stronger) - so powerful that I have a hard time imagining this talent making it live.
The Bad: Vow of Unity is really hard to judge since there are so many unknowns about it, such as duration. I suspect that Void Shift will be a no-brainer for shadow priests as the other two talents are both healer-centric. It also has enormous griefing potential in the currently suggested incarnation - in battlegrounds for example you could swap health with some poor random schmuck whenever you're close to dying and get them killed instead.
I think that even if I agreed that another talent revamp was badly needed, I doubt that I would be happy with this system in particular. People are complaining about the prevalence of cookie cutter specs in the current system, but as a healer this doesn't affect me nearly as much. As a holy priest I'm free to choose between a variety of talents to boost my hps, mana regen, cooldowns or effectiveness of different spells, all depending on my preferred playstyle, and they are all equally valid.
A reduction to six talent points is less than what I currently get to contemplate, and about half of them don't even affect any core abilities. A few of the new abilities sound very cool in principle, but it remains to be seen how frequently they will be used.