Arena now takes up a LOT of my spare time. I'm happy with the microtransaction system. $5 can take you pretty far when it comes to building a competitive deck if you are willing to play drafts. I've spent around $40 total across three accounts. The $5 one-time purchase is quite generous.
BO1 constructed allows you to deviate from the meta and/or counter it. The matchmaking is good, and you can tell a lot of effort has gone into cosmetic and sound effects.
I've played lots of Hearthstone and Shadowverse since both came out. I haven't touched Hearthstone in years, even though I spent close to a thousand dollars on it. I'm done with HS for good. I'll still play Shadowverse for new sets since you can always make a competitive deck for free if you create a new account and spend a few hours grinding.
I hope Wizards doesn't get greedy with Arena as it (and MTG) continue to grow in popularity. When Hearthstone got big, I expected Magic to die out completely, but it's nice to see that didn't happen.
Arena has been so fantastic for me. I spend a fraction of what I used to, have all that space back in my apartment and play way more than ever. There are some things that I miss about playing face to face with people, but also there's no way I'd ever play some of my combo decks (any Mirror March...) in paper.