The Paladin changes we've seen so far have been pretty massive. There's been a reworking of our Seal and Judgement system, a shuffling of our talents, and the addition of interesting baseline spells like Divine Plea, a much needed mana recovery mechanic. The important thing to remember, though, is that this is Beta -- meaning a lot of things can still change from now until Wrath of the Lich King goes live. And as Ghostcrawler indicated, a lot of things will change.
In fact, some spells we might love now could change or be scrapped. The Art of War, a talent I raved about and was wreaking havoc in the Beta, was fundamentally changed. From a pure DPS talent usable by raiding Paladins, it has become a utility spell more geared towards PvP. Some old spells such as the poor man's Divine Shield, Divine Protection, was reworked to actually be more usable. While we won't go through all the changes one by one -- there are a lot and I expect more in the future -- we can examine some key changes and try to figure out what Blizzard wants to do with the class.
One of the big changes was the removal of Forbearance from Avenging Wrath, and how it now affects healing, too. Another big change, however, was the extension of Forbearance to three minutes, up from one. This is likely a response to the rework of Divine Protection, now an option among a Paladin's impressive array of defensive spells. Because it is now a damage mitigator rather than an immunity, it is easily usable by Protection Paladins while tanking, increasing the usefulness of the spell a hundredfold.
Spells scaling off Spell and Attack Power
Blizzard has also allowed more spells to scale with both Attack Power and Spell Power, such as Consecration and Exorcism. This should make both spells, particularly Consecration, more viable for all Paladin builds. This is part of Blizzard's effort to streamline the game to depend on fewer types of stats. Furthermore, the trend has generally leaned towards making all specs DPS-viable -- not necessarily in a dungeon or raid scenario, but for personal utility. It will no longer be as painful to kill mobs as a Holy Paladin, for example.
Leaner talent trees and seal system
The Beta also sees our talent trees slimming down, with some talents such as Pursuit of Justice reduced to 2 points for almost the same effect, and the removal of Precision. Blizzard has said that players should easily be Hit capped through items and enchants and wanted to free up talent points for more useful abilities. They seem very focused on trimming down the game to bare essentials, with key stats coming from several places thus allowing players to focus more on gameplay. Seals are all now one rank, last 2 minutes, and are no longer consumed by any of the three Judgement spells. Paladins no longer have to micro-manage Seals but concentrate on the more fun spells like new strikes.
Single stat focus
I don't know how this works in practice just yet, but with the move to have Retribution Paladins share Warrior (and Death Knight) gear, there will be a sharp drop in total mana with the absence of Intellect. This is what makes talents like Judgement of the Wise so important. Then there are talents like Sheath of Light and Touched by the Light, which increase spell damage based on the appropriate stats. Paladins -- a hybrid class -- now have the freedom to concentrate on one important stat rather than a host of different ones. Holy Paladins will pursue Intellect, Protection Paladins will stack Stamina, and Retribution Paladins value Strength (or Attack Power). Everything else follows.
Nothing is set in stone right now, but it's pretty clear that Blizzard has learned so much about the game and is streamlining the class incredibly well. With the changes so far, it seems like Paladins will finally become a more engaging class to play and not just a glorified auto-attacker, reactive tank, or single target healer. Ghostcrawler did mention that they'll be 'tweaking' Beacon of Light to fit the Paladin's "kit" a bit better -- which could mean that they still want Paladins to fill a strong single target niche. Regardless, it looks like the class is finally getting some healing flexibility. It might take some time before we see any more major changes but I'm excited to see where this road leads because, if Beta is any indication, it seems like Blizzard finally knows what to do with the class.