I just started this weekend. I'm doing fine, but still don't really understand all the terminology and it's kind of fucked me over a bit. Was also going to try out Hearthstone soon as well.
Hearthstone was alright, but the gameplay, for me was pretty lame. Wasn’t super into Gwent when playing Witcher 3. You should check out Magic: The Gathering Arena on PC if you can. There will be a mobile version some time later this year. It’s far superior to Hearthstone.