Beta - http://www.neogaf.com/forum/showthread.php?t=755759
OT1 - http://www.neogaf.com/forum/showthread.php?t=782919
OT2 - http://www.neogaf.com/forum/showthread.php?t=878696
OT3 - http://www.neogaf.com/forum/showthread.php?t=1008907
OT4 - http://www.neogaf.com/forum/showthread.php?t=1086390
OT5 - http://www.neogaf.com/forum/showthread.php?t=1131872
OT6 - http://www.neogaf.com/forum/showthread.php?t=1201002
OT7 - http://www.neogaf.com/forum/showthread.php?t=1238073
OT8 - http://www.neogaf.com/forum/showthread.php?t=1311864
What is Hearthstone?
Hearthstone is a free-to-play online Collectible Card Game (F2POCCG, which is a real genre) from Blizzard, based on the Warcraft universe. Choose a hero corresponding to one of the nine classes in Vanilla WoW and create a deck using their signature mechanics to fight other players in Casual or Ranked matchmaking. Earn Gold for every three wins and use the Gold to buy booster packs in order to expand your card pool, or use the Gold to purchase a ticket to the Arena where you construct your own deck on the fly using a random pool of all cards in the game. There is no offline play, but there are singleplayer adventure modes.
Download the client (Windows, Mac) on the main site. Note, you will also need a Blizzard account to log in to their launcher.
How to play Hearthstone?
I'm not going to go into that here, just play the tutorial to learn the game.
How to really play Hearthstone?
Read articles, apply critical thinking, watch good streamers.
Is there an in-game/player-driven economy?
No. There is no card trading or buying cards from other players and there probably won't be anytime in the foreseeable future. In its place is a crafting system. You can disenchant cards you do not want for arcane dust. You can then use that arcane dust to craft cards you do want.
Is this game Pay2Win?'
Of a sort. The thing you should know about Hearthstone is that if you're not going to pay money, plan on playing a lot (read: grinding) or becoming really good at Arena. The longer a player has played, the bigger their card pool will be. This means that an older, frequent player will always have better cards than a newer player. This is just an unavoidable part of collectible card games.
A paying player can save a lot of time by buying boosters, but it's not cheap and they're not guaranteed the best of the best cards, which is, in the end, what separates good decks from the best decks. Buying some boosters right off, however, will help you build a foundation to reliably win games in order to get Gold.
If you really hate not having good cards, then stick to Arena, which is a "level" playing field for a certain definition of "level".
What's the balance like?
This far post release, the Hearthstone team is committed to only affecting balance changes when they are "absolutely necessary".
If I like MTG/YGO/blah blah blah, will I like this?
Hearthstone is simplistic compared to games like MTG and YGO. The reason for this is because of Hearthstone's asynchronous turns, which means that you can't make any moves on your opponents turns. Hearthstone does have it's own particular brand of complexity, but it's really designed from the ground up to be a "pick up and play game". If you're looking for a hardcore card game experience like MTG, you won't find it here, but if you're looking for a streamlined card game experience you can jump in and out of whenever you want, then Hearthstone is right for you.
Anyway it's free, so you don't lose much by giving it a shot.
NeoGAF Hearthstone Discord Channel
Le Reddit Guide - Probably the best place to start if you're totally new.
Trump Teachings - A video series by one of the game's most notable streamers. This is essentially Hearthstone 101 and is mandatory viewing for any new player looking for a crash course in Hearthstone strategy.
Liquid Hearth's Beginner Guides - Some of the info is outdated but the general ideas remain the same.
Three Competing Resources Parts 1, 2, 3 - A series of articles on "resources" in the context of a card game, which goes well beyond just mana.
Official Forums - A veritable nest of QQ and cries for nerf, just like your WoW days!
Team Liquid's Hearthstone Portal - Better place to discuss and learn about Hearthstone, frequently featuring competitive analysis and deck tech articles.
IHearthU - Another good site for high level Hearthstone discourse.
Hearthpwn and Managrind - Part of the Curse family of gaming sites, not only does it have an online database of cards and deck building tool, it is also home to ManaGrind, one of the premiere Hearthstone tournaments!
Hearthstone Wiki - Obligatory game wiki.
HearthArena - This website will help you out while drafting for arena. You enter the three cards you are presented for each pick and the tool will attempt to recommend you the best pick based on a general tier list and your current deck.
Gutshot's Hearthstone Collection Spreadsheet - You can use this to keep track of your current card collection.
Official Blizzard Channels: YouTube, Twitch. Blizzard's Official YouTube/Twitch channels. Used for officially sanctioned tournaments and announcements.
Amaz: YouTube, Twitch - Over the top reactions. Says "That's a card". Constructed and arena.
Brian Kibler: YouTube, Twitch - High level, very professional streamer. Former MTG Champion. Doesn't usually play meta-decks. Constructed-only.
Disguised Toast: YouTube, Twitch - Variety video content and fun streaming.
Forsen: Twitch - Popular yet very salty stream. Politically Incorrect. Twitch at its best/worst depending on who you ask. Great if you're a high schooler who needs an angry father figure in their life.
Hafu: Twitch - Very high level arena play.
Kolento: YouTube, Twitch - Very high level stream.
Kripparian: YouTube. Twitch - Very popular stream. Very chill. High-level arena play. Good YouTube content.
Reynad: YouTube, Twitch - Pro player who nonetheless probably hates the game and his life. Some of his donators sexually identify as attack helicopters.
Trump: YouTube, Twitch - Nice guy. Lots of good YouTube content. Constructed and arena.
Funny and Lucky Moments (Trolden): YouTube - Crazy play montages.
Epic Plays (Rage Orc): YouTube - More crazy play montages.
Hearthstone Science: YouTube - Advanced Rules Experimentation and Discovery
Team Liquid Calendar