(Not so) Quick rundown of all the cards from my perspective.
Druid
Mark of the Lotus - Cheaper yet less flexible Power of the Wild. I'm not sure how I feel about it. Maybe an all out token Druid runs all four.
Pilfered Power - Druid has so many options to ramp now that I'm not sure how this fits in. Darnassus Aspirant was pretty much abandoned due to being unreliable so I can't imagine Druid flocking to this all that much.
Lunar Visions - Insane, potentially broken. The one thing going against it is that Druid is very spell heavy right now. That said, this is an auto include in any Druid deck that runs a good number of minions in my opinion.
Kun the Forgotten King - Not sure how I feel about this quite yet. Obviously it has some insane combo potential but I feel like this a card like Aviana that will end up being underwhelming.
Hunter
Piranha Launcher - Too expensive for a 2 attack weapon. Spawning the 1/1 is nice but it doesn't seem impactful enough to make up for the underwhelming stats on the weapon.
Mage
Manic Soulcaster- Seems ridiculously good to me. Can't see a reason why you wouldn't play this in most Mage decks.
Paladin
Getaway Kodo - Doesn't seem particularly noteworthy. Pretty much always going to hit the Defender from Noble Sacrifice in Secret Paladin. Whether that's good enough, I'm not sure.
Meanstreet Marshal - Potentially a very strong effect, just not sure if this Zoo/Buff Paladin Blizzard seems to want is actually going to take off.
Small-Time Recruits - Again, potentially strong in the right deck. I'm just not sure that deck is there right now. Helps that Paladin has Selfless Hero which is a decent card as well.
Wickerflame Burnbristle - The effect isn't particularly great as healing in the early game is usually not worthwhile. Obviously has the advantage of trading really well (like Minibot) but whether that's enough for it to see play, I'm not sure. Potentially insane if you can buff it though.
Priest
Pint-Size Potion - Obviously has great synergy with several Priest cards but does the class really need more combo based removal? That said, in a minion based deck like Dragon Priest this seems really good for forcing favorable trades.
Potion of Madness - Very strong depending on the meta. Obviously great against aggro, less so against control. Although snagging something like an Acolyte of Pain is still useful.
Kabal Talonpriest - It's insane. Likely goes in most, if not all Priest decks for the forseeable future.
Drakanoid Operative - Two of in Dragon Priest, no questions asked. Very, very strong.
Dragonfire Potion - Probably the final piece of the puzzle for Dragon Priest. From what has been shown so far, it has the potential to be a tier 1 deck in my opinion. Does have the weakness to Azure Drake though.
Rogue
Counterfeit Coin - Is the coin worth a slot or two in your deck? I guess it's time to find out. Wouldn't surprise me if this becomes staple in some Rogue decks.
Lotus Assassin - Solid card but I struggle to see how it fits into what Rogue tries to do currently.
Shaman
Nada
Warlock
Nada
Warrior
I Know a Guy - Potentially strong, solely because of the versatility. There are a lot of solid/good taunt minions that don't make it into decks but could be very strong as part of a discover like this where you can choose one that best fits the situation.
Grimy Goons
Grimestreet Informant - I'm not sure that Hunter, Paladin or Warrior are in need of a discover mechanic like this. Warrior is the class I could see make the most use out of it though.
Jade Lotus
Lotus Agents - Rogue could maybe have some interest here. I don't think Druid or Shaman have any reason to bother.
Kabal
Kabal Courier - The strongest of the three tri-class discover cards in my opinion. I think it fits reasonable well in a Reno deck, something Warlock and Mage can pull off and something Priest has dabbled in.
Kazakus - Seems to be a really strong effect, albeit with a deck building limitation and three class restriction. That said, I think all three classes have Reno potential so I think it will definitely see some play.
Neutral
Mistress of Mixtures - Great card, most likely a death knell to face decks. Renolock loves it, other decks could potentially find a place for it.
Patches the Pirate - Immediately goes in Pirate Warrior. A staple in pirate decks going forward.
Friendly Bartender - More neutral healing, although not as powerful as Mistress of Mixtures. Without much aggro on the ladder I don't see this being in consideration.
Fel Orc Soulfiend - Priest immediately comes to mind. Even aside from that it seems like a minion with relatively strong board presence in the early game. Not sure where it fits exactly but it's definitely interesting.
Kooky Chemist - Could be decent but it's not like Crazed Alchemist sees all that much play at the moment. Probably doesn't see much play really.
Second-Rate Bruiser - Probably not worthwhile. Cyclopian Horror served a similar purpose and hasn't seen much play at all, though granted this card is probably a bit more reliable.
Finja, the Flying Star - Very cool card and I think it has potential in Anyfin. While it does dilute your combo a little bit, the trade off of pulling the murlocs out immediately is potentially very, very strong especially for a combo deck that already focuses on cycle. It'll be interesting to see what happens with this one.
Big-Time Racketeer - Nothing too special about this one. Seems like it could be pretty solid for Evolve decks. Obviously a significant nerf to Moonglade Portal.
Wind-Up Burglebot - Cool card, but I can't imagine it being strong enough at 6 mana.