So, Planeswalkers.  Frankly, I'm a purist.  I feel that some aspects of Magic shouldn't change.  One of those is the card types.

My opinion on the matter is pretty simple.  Basic rules and tools of a game are the foundation of any successful, fun game.  Magic, as an expandable game, is incredibly complex strategically and functionally.  As a result, not only is the barrier of entry high, there are several of them.  First, you gotta learn how to play.  Then, you have to learn how to play well enough to no longer worry about rules and such on a conscious level.  Then, if you want to play in tournaments, you have to learn how to play well enough to compete.

When you add a new basic rule (say, a new step between Upkeep and Draw), a new color, or a new card type, you up the barrier of entry at all levels.  I feel, for everyone but established players, this is a bad thing.  You want the game to be challenging, but not at first.  The challenge should be what keeps you involved.

Before we move on, here's the rules regarding Planeswalkers according to InQuest (this info copy-pasted from http://forums.mtgsalvation.com/showthread.php?t=87932):


- There cannot be more than one Planeswalker of a given type in play (not sure if this means each player can control one, or if it works like legendary)

- A Planeswalker comes into play with loyalty counters equal to the number in the lower right corner.  These function as "life points" for the Planeswalker

- Each ability of a Planeswalker can be played by adding or removing the appropriate number of loyalty counters, listed as the cost of the ability.  Only one ability can be played per Planeswalker per turn, sorcery-speed.

- When you declare an attack, any number of your attacking creatures can be declared as attacking a Planeswalker.  Each one damage dealt means one loyalty counter is removed.

- Any number of creatures the Planeswalker's controller controls can block creatures attacking a Planeswalker.

- Whenever a spell or ability you control would target a player, you can target a Planeswalker instead.

- Whenever a Planeswalker has no loyalty counters on it, sacrifice it.  This is a state-based effect.

The Planeswalker card type adds an interesting dimension to the game.  As cards, I can't decide if they add to the flavor or diminish it.  Dealing damage directly to a player, or attacking a living person, for example, is flavor that appeals to fantasy junkies and hardened tournament players alike.  "Smashing face" and "burning your face" is decidedly less exciting when talking to a pseudo-player represented by a card.  However, the flavor of controlling a "lieutenant", as it were, to cast spells as your underling is quite cool as well.  But then again, that's what Spellshapers were.  So I don't know.  I feel like it's a negative.

That aside, it's interesting.  Liliana and Garruk are both powerful cards with powerful effects.  Liliana is a control powerhouse, a win condition against aggressive decks and a powerful card advantage machine.  The first two abilities can quickly take control of any matchup.  Five loyalty is quite a bit to start out with, keeping her out of direct damage range (because five, of course, is a functional six) and coming down the turn after Damnation hits is good, too.  In fact, the synergy between the first and third abilities is huge, forcing your opponent to play out their creatures into your removal.  Once the board is swept, you reanimate their entire army.  If you could give her Flash with Teferi, she would be an auto-play in Teachings.  Sadly, that doesn't work.  She will still see play in Black-based control, however.

Garruk is simply nuts.  Consider this simple play:

 Turn 1 - Llanowar Elves

Turn 2 - Call of the Herd or Troll Ascetic

Turn 3 - Garruk, untap two lands, cast a random dork (Kavu Predator, Tarmogoyf, Riftsweeper, Grizzly Bears, anything.  Let's assume a 2/2.)  Swing for 3.

Turn 4 - Might of Old Krosa, Blachwood Armor, and/or some kind of Haste guy (like Groundbreaker), sacrifice Garruk to Overrun, swing with a 4/4, a 6/6, a 5/5, and potentially a 9/4.  Or scratch the 9/4 and give one of those guys +4/+4.  Either way it's lethal.

So many of those cards are interchangable.  In fact, we have a precedent for this kind of deck.  Let's take the MonoGreen aggro deck from Nationals and update it for Lorwyn Standard:

MonoGarruk Beats

16 Forest

2 Pendlehaven

4 Treetop Village

4 Llanowar Elves

4 Boreal Druid

4 Thornweald Archer

4 Troll Ascetic

4 Scryb Ranger

4 Groundbreaker

3 Wren's Run Packmaster 

1 Timbermare

4 Might of Old Krosa

2 Loxodon Warhammer

1 Stonewood Invocation 

4 Garruk Wildspeaker

This deck is quite explosive, and takes advantage of Wren's Run Packmaster quite well.  You have twelve Elves to Champion, giving your mana Elves a solid late game (besides growing to 4/4 tramplers) and allowing you to situationally reuse Riftsweeper and Viridian Shaman as well out of the sideboard.  Wren's Packmaster forces a Wrath right away, and active Packmaster is insane with Garruk.

Ultimately, flavor aside, Planeswalkers are a great addition to the game.  They increase the power of the Red cards, of course.  Direct damage will be the best way to eliminate Planeswalkers.  I'm not sure if it works the way I want it to, but I wonder if you can opt to give your Planeswalker a loyalty counter in exchange for each point of life you would gain.  If that is indeed the case, cards like Tendrils of Corruption and Reviving Dose become much more attractive with a Planeswalker in play.

Seems interesting, if gimmicky, to me.  I like these cards as a player, but I like all cards as a player.  Game on!