I tried it out a bit, I like the story mode and the way cards upgrade and stuff. The 2 lanes with various different effects in different battles is an interesting idea as well.
The lanes only have different effects in Story Mode and Solo Arena. In all forms of Versus play the left lane is vanilla and the right lane is Shadow, which gives all minions played there Cover (making them unable to be attacked on the turn they are played). There is a support card in Agility that turns all lanes into Shadow Lanes, though, which raises the possibility that other abilities may get similar cards.
The more interesting thing to me is the catch-up mechanism. Each player has five Runes, which break the first time you go to 25, 20, 15, 10 and 5 life. When a Rune breaks you draw a card - and if that card has the Prophecy keyword you can also choose to play it immediately for free. This creates a balancing act: you often don't want to throw everything into your opponent's face because he'll draw more cards, but you might be forced to give him one card in order to set up a lethal attack next turn.
Once you get out of Story Mode you'll find that rewards are more generous than Hearthstone in terms of cards but less generous in terms of gold. As in Hearthstone you will only recoup your Arena entry fee if you win 7 games, but Versus Arena
ends at 7 wins so going infinite is basically impossible. However, you will gain more gold for winning in Versus Ladder (up to 150 a day) in fewer games plus you also get a card with each three wins. In Arena you get one guaranteed pack plus a second pack from around 5 wins and a third if you go 7, plus some Soul Gems and a card that increases in rarity the more wins you get.
Crafting: decks in TESL are 50 cards against 30, the card copy limit is 3 against 2 and most legendaries can also be run in multiples. However, Legendaries are 1200 Gems against 1600 Dust and are a bit easier to acquire (roughly 1 every 20 packs against 1:30 in HS, plus rewards for Arena success). Overall crafting cost is comparable by deck size - a solid HS deck will be 8-10k Dust, an equivalent TESL deck will be 12-15k - but cards are that bit easier to acquire in TESL.