Rewards for playing vs AI help new/inexperienced players not get obliterated in constructed, and keeping cards you draft helps you build the collection you want without simply opening packs.
You can win with weapons, spells, units, and strategies of all kinds. Brewers and casual players can explore a near-infinite variety of fun decks without tanking their win rate.
This game is not as complex and deep as MtG, but still it requires a lot more of strategic thinking and deck-building skills than HS. At the same time, a game of Eternal can usually be finished within 10 minutes.
Best played on a PC or a tablet. Playing on a phone can be difficult as it's a direct port from PC so text and images can be tiny. Not a problem if you're familiar with the game, but new players it will be frustrating.