I was surprised to not see a thread for this excellent game here, so starting one of my own!
Some personal thoughts:
* I have no previous experience with League of Legends, so no nostalgia factor for me. My opinion of the game is solely based on the gameplay and what it has to offer.
* Coming from Hearthstone & Duelyst, this game definitely seems more complex & less intuitive at start
* For example: there are several types of mana, there are defense turns and attack turns, there are turns within turns (as in - you and your opponent can respond to every action, even if it isn't your turn), there are several 'speeds' for spells, etc.
* There is a nice tutorial (which I'm sure will improve after the beta) and the learning curve is worth it!
* The game gives you three full pre-made decks to play with, I suggest doing the prologue missions, then a few games vs AI and then unranked vs a human opponent
* Once you get the hang of it, the gameplay feels great. Matches are interesting and so far I didn't run into that oh so familiar 'what is this RND bullsh*t!?' feeling
* Progression system feels great and rewarding. I'm still early in the game but it feels like I can just earn a lot of cards by simply playing and doing daily quests
* Each faction can be leveled up separately. It is told that the most efficient way is to level up each one to level 4 and the take it from there
* There are weekly rewards that can also be leveled up by playing, pretty cool!
* The development team believes that the money should come from cosmetics and the cards should be acquired through playing... so while it is possible to buy some cards with real life money, that option is very limited and resets per week. I have never seen a game that limits you with money you can spend. I like it!
* You can't drop in rank once you reach it... takes the anxiety factor away, I like it too!