I don't like the fact, that only one spell interacts with the planeswalker. And most of them do it in a very underpowered way. The other card each planeswalker has often doesn't really fit into a deck build around the planeswalker and could be better.
Last but not least. Maybe you should create an edh-like format, where a planeswalker is your 'general'.
Ajani
The analysis:The mantra is just too weak and the Pridemage just to selfish. If you can get a 2/1 for casting cost 1, why shouldn't it be possible to get a card that gives you 1 life per turn for cmc 1. Therefore a
Sun Droplet 
is a much more flavorful card for Ajani, as well as a
Cradle of Vitality 
or
Well of Lost Dreams 
.
The deck:In an deck built around Ajani...
a) you should get a huge bonus for gaining life
b) you should have a lot of creatures
c) you need some sort of lifegain
d) you need some sort of evasion & protection for the final kill
A
Kinsbaile Borderguard 
was quite fine, but he didn't read 'when he leaves the battlefield'. And I am not a fan of white having tokens. Tokens are not very individual. I tried to combine Ajani with my Rebel deck, but he doesn't really fit in there... and doesn't solve the problem of a rebel deck.
Therefore the
Ranger of Eos 
is one of the best white cards, but he has the same converted mana cost as Ajani. So this is a minor drawback. The
Squadron Hawk 
s aren't cats, but get close to what you want. The effect is limited to a maximum of 4 copies (like a 'pride')and to a specific card. It's not like a
Goblin Matron 
, where you get only one card, but you're not limited to a specific card. If you search for another Matron, you could get similar results to the Hawks... getting all your copies into play.
Therefore, I would have made the Pridemate like the Squadron Hawk without flying but higher P/T rating (maybe a 3/1 for
). The mantra
(a calming presence???) should have been something like "whenever you gain life, pay ???. If you do, target permanent doesn't untap during the next untap step" or something that uses life-gain to produce damage prevention or color protection. And it should have been an enchantment for cmc3 to keep the mana curve right, allowing early creatures.
Jace
The analysis:First of all, I don't like the fact that blue uses mill-effects. I know that this is a historical tradition, where you only need to have a deck full of counterspells and an alternative win condition (
Millstone 
). But the win-con wasn't and isn't such important.
Milling however, is a nearly useless ability, unless you mill the whole library or use the cards in the graveyard. In other words, it's risky, you can't rely on it, supports graveyard use and is highly random.... so it's an easy call:
It's a red!!!
Especially mass-milling.
Extract 
on the other side grants a card disadvantage for a specific task: denying the important cards. It's a search effect instead of a random "top X cards", so it's much more relyable and much more
blue.
Card draw effects are also random, luck-based effects, but grant a useful, but slow way to win in long terms. So this is neither blue (luck-based), nor red, but
white. Letting all players draw cards is even more white. Searching cards or reorder cards are a much better way for blue.
Let's imagine a world of magic, where blue doesn't have the old counter+instant draw option and has no useless mill effects. Instead, blue uses it's intellect to put the right cards on top of his/her own library... and puts the wrong cards on of an opponent's library on top of it (or the right cards out/on the bottom of that library).
Then, blue would harmonize with white using draw spells, but would fear the red mill effect that would ruin the exact order of the cards... what a perfect situation. Opposing colors hate each other and befriended colors support each other.
So I can't like the new blue Jace cards, no matter how good they are. And I don't want to think about a blue deck, where the player was focussed so much on mass-milling, that he survived with just one life, but completely milled an opponent's deck. This isn't a blue way to win... it never was. But it is supported so much by R&D, that it makes me a sad panda.
Liliana
The analysis:As already mentioned, searching the library and putting the card on top of it, is a blue ability in my opinion. Adding a 'life-loss' doesn't change the fact. In addition, a black mage tries to domiate others and hate anything that doesn't grant an instantaneous power bonus. It's more a 'get the bonus now and pay the price later' than vice-versa.
Therefore, the second ability would have been an ability for Jace, where the 'pay 2 life' is replaced with 'pay 2 points of loyality'. It would have been much more a black ability, if you would really draw the card.
Liliana's specter feels like a multiplayer card, But if you want to die, try that one and feel the consequence, when you've become a public enemy. The low toughness doesn't feel right either.
The Megrim 
-power-up card Liliana's Caress 
doesn't feel right either. First of all, if you play a black discard control type of deck, you need the early turns. You don't want to waste a turn 2 slot for an enchantment. It's better than wasting a turn 3 Megrim slot, but still doesn't feel right. I believe that R&D has forbidden the cmc2 discard slot. Players would rather play 2 cmc1 discard cards and a Hymn to Tourach 
won't have a comeback in the next few years. And of course: The turn2 slot has enough creature destruction cards.
The deck:
T
he early slots are full with discard control. The mid-game slots (like the specter) establishes a permanent discard control and should handle the board, if some creatures have slipped through during the early turns. The finishing cards shouldn't really focus on discard, but rather on reanimating the creatures your opponent has discarded and you'll have a nice black deck.
Liliana should have a casting cost of 4. Any additional mana cost means that you either have a dead card, you have to put additional lands into your deck or you have to focus on mana acceleration. But Lilliana is as she is. A quite useless, too expensive women that could be used in MBC decks rather than discard decks.
I would have made a Specter that combines power with a discard effect. Something like a 1/1 with
'Whenever Liliana's specter deals combat damage to a player, that player discards a card' and
'Whenever an opponent discards a card, put a +1/+1 counter on Liliana's Specter'. A Mind Rot 
would be a additional +2/+2 effect. The more despair you create, the more powerful he becomes.
Liliana's caress should be something with cmc2-3, that helps even more to establish board control. Maybe it could also increase your amount of mana... like the Cadaverous Bloom 
did. This would make it possible to play Liliana a few turns earlier. Something like a Phyrexian Totem 
. However the Negator Totem isn't able to establish board control. Therefore anything that prevents your opponent from attacking or playing spells would be a much better choice.
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Chandra and Garruk will be in an other reply.
