I'll be honest - the momentum of the playtest packet has waned, and so goes my interest. But I'd like to complete this series on my impressions. So here's the Cleric.
The basic framework behind the Cleric is extremely solid. By virtue of its being a spellcasting class it's inherently customizable. Prepare whatever spells you want to achieve a specific playstyle. The spells themselves are pretty much what you'd expect, so I won't get into specific details here. One thing that bears mentioning is that I'm not too happy about how important magical healing is, but I admit that that's personal preference. I have players in my group that are of the opposite opinion. That's what compromising is for (besides, I doubt there's anybody that likes every single element of any one game).
More important (at least in my opinion) is that the Cleric isn't relegated to "necessary" status. Fortunately, that's not the case. As you'd expect the Druid is another "full caster" that has ample healing, and given the increased spellcasting ability of Paladins and Rangers compared with past editions and Clerics are hardly necessary. Indeed, to compare the state of available healing with 4E it's worth noting that so far we have a class from each of the four roles that can heal, even if the classes aren't quite as married to those roles (i.e. Druid isn't necessarily a controller in Next). This is a good sign, because it suggests that as other "Leader" classes are designed they're likely to have more than enough healing to get by. If a Ranger specced for healing can do a decent job of keeping the party up, I'm sure a Bard, Shaman, or Warlord would be more than capable.
Because ultimately spreading magical healing out amongst a wide variety of different archetypes makes magical healing as a critical party function a much easier pill to swallow.
Something that I've seen suggested a lot since these playtest packets have been released is making deities an important aspect of a Cleric's playstyle. This packet really delivers on that front, with deities possibly affecting armor proficiency, what cantrips you automatically get, what domain spells are "auto-prepared," and what Channel Divinity options you have access to. Who you worship has a big impact on how you're built.
Now, I've complained about the lack of customization for some of the classes in that your choice of "build" at level 1 determines pretty much everything you get. The Rogue is especially bad for this. While that's essentially what choosing a deity does for the Cleric, there are some important differences to keep in mind. The most obvious (and one that I already mentioned earlier) is that Clerics will still be customizable regardless because they can choose to prepare whatever spells they want. Defensive buffing, offensive buffing, healing, control, utility, etc., you have a pretty broad spectrum available to you. But the other major difference is that having so much decided based on deity is more desirable than Rogue schemes (for example) because there's a strong tie to the game world. In other words, Clerics get their power from the gods so it makes sense that a god of Trickery is going to give the Cleric a specific set of specialized abilities that are different from a Sun god. From a narrative standpoint it also reinforces a player's choice of deity, keeping it in the spotlight. The deity is important to the Cleric (in the game world), and so it's important to the player.
It makes a lot LESS sense for a Rogue to ALWAYS have all of their abilities lumped in specific "packages."
The deities themselves are pretty generic, keeping them open to be fit into any pantheon. This also opens the players up to seizing narrative control by making up their own details about the pantheon. As a DM I prefer leaving this stuff up to players, and I'd rather have them fill in the narrative blanks as opposed to simply picking a god out of a list.
I like the choices that are given. The Arcanist allows for an "arcane dabbler" type Cleric, the Lifegiver is the healbot, the Lightbringer is the "laser Cleric" or white mage archetype, the Protector is a defender/defensive support option, the Reaper is your death god (awesome, because The Raven Queen was quite popular in a lot of 4E groups), then you've got the Stormcaller (your typical flinging lightning, bow before Zeus type guy), the Trickster (Rogue-lite, but with spells!), and the Warbringer (the martial "crusader" Cleric with the best armor and weapons).
A minor point, but Advantages on all Int checks to recall religious lore establishes the Clerics as the go-to guy when it comes to that sort of thing, despite a (likely) minimal investment in Int.