Count me in the group as anti-mounted combat as a class feature. I love paladin's, but riding a horse is generally used as a mode of transportation, and absolutely no use in a dungeon crawl or in 99.9% of skirmishes that will take place in the average D&D campaign. Mounted combat is something cool that pretty much anyone who doesn't strike from the shadows should be able to build into if the campaign presents room for mounted combat to exist. Otherwise it's highly finicky and generally doesn't com in hand or come out as cool as it sounds.
"Knight in Shining Armor" is a direct reference to a feat that was available in 4.0(don't recall if it was in earlier editions). It was a pretty useless feat save for when you're all stuck in a 10x wide corridor. In the open field to avoid being AoE'd to death, the party spreads out, and thus, makes the "adjacent to the Paladin" bonus pointless.
You know what I'm really not liking as I read through this article? The emphasis on the Paladin being a defender. The Paladin has many roles, defender among them, and if 5e is supposed to be anything it's supposed to be an edition with options. Even the 4e basic paladin straight out of the PHB1 could be given a two-handed weapon and turned into a holy striker of pretty serious proportions.
And as people have already pointed out, while a lot more of what you're going to be fighting is probably evil, smite "alignment" powers were always very fiddly. Sure, they're great for hordes of undead or demons and so on, but in games were alignment is more of a perspective and less of a hardcoded "these guys are evil.", it really doesn't come in handy as much. I would love to see smite simply be "Smite: add extra X damage to your attack." I mean, I love playing the honorable, knightly, borderline lawful stupid Paladin, but I'd like to be able to use Smite more than once every month(in game). I mean, if they're going to make Smite's damage some serious hoodoo, sure, give it a restriction! But when all I'm getting is a +1d6 damage, guys, that ain't a bonus, that's standard fare.
Personally, Wizards is already copying Paizo to get a good idea of where the Rogue should go, they oughta keep up the good copyright infringement and look at how Paizo did up the Paladin.
Auras? Great feature. Static effect that can harm enemies or aid allies, few to no other classes have this feature.
Lay on Hands? Traditional. Paladin's have always had a few backup healing features as divine characters. They're no cleric, but they'll be able to lend a Hand in a pinch.
Smite? Great feature, though some other classes have this, I don't think it would be difficult to tailor it to the Paladin without giving it awful stupid restrictions like only allowing it to affect Chaotic Evil.
Mounted Combat? Cool feature, maybe the Paladin is better at it, but really it's not going to see use in most games. The battlefield simply isn't suited to it.
Defender? A good option, Paladin's should be great defendes, right up there with Fighters. But they should also be holy avengers, heavy-armored "smite your face in the name of my god!" type guys. It's the same duality of the Fighter. I don't know if there's room for a two-weapon Paladin, but there definately needs to be room for a two-handed juggernaut.
I don't like how niche they're looking. There's plenty of fat to trim from the Cleric to give the Paladin more space. If they're not willing to give the Paladin some room between Fighter and Cleric, then the Paladin might as well be a multiclass prestiege class option(which I don't want to see, I love paladins as a base class).