So I gave SolForge a shot since it's free, and I'm still without access to the Hearthstone.
Played through the tutorial and uninstalled it. There is something to be said for the presentation and attention to UI that Blizzard gives their games. The whole SolForge package was incredibly cold and uninviting. Especially for someone who has never actually played a game like this, there was zero effort to explain things. Where as the few times I've seen Hearthstone, it's been incredibly easy to follow what is going on and why.
Granted, SolForge isn't "released" yet either, and I'm sure they don't have the amount of money to throw around like Blizzard does - but what an unwelcoming experience.
Yeah, I've put over 20 hours into SF and watching Hearthstone videos, it's night and day from a presentation standpoint. I doubt I play it anymore once I get a key for this game.
That said, every virtual card game I've played has mediocre UI at best.