I'll share my experience.
I started with a card pool I would rate "decent". It was mostly red cards, I had
Wake of Destruction, a 4/3 flying haste dragon for 5, some direct damage spells. I was also able to by various more direct damage spells relatively quickly (blaze, fireball, incinerate, lightning blast etc).
I won the first 17 or so matches without losing any (I did lose a few single games but not often).
Then the AI started ramping up. (I selected Normal difficulty by the way so it's not like I play ultra hard or anything)
I lost like one out of 4 on normal, which is fine. I did feel I'm only winning because I play red during this time : When the enemy creatures were too strong to handle using my own, I could use direct damage to kill the opponent directly. The bird pet helped a lot with that, providing 1 damage per turn for most games. In most cases I was able to nuke the creatures, too.
About 10 more wins later, AI is not playing hard decks. I win 1 out of 4. And would win zero if I weren't playing a deck full of nukes that double as "deal damage to enemy player" if needed.
I still haven't been able to unlock getting more than 1000 per card, and I still receive like 23% when selling cards, so I have no way to get any decent money. Buying packs is not an option.
I entered a draft M15 tournament once for 1200 using up most my savings. I got good cards and was able to walk away 1st place, happyness. (didn't get much red cards to use, but lots of other cool stuff...don't think I have enough to make other color decks yet, especially not at hard level.)
I also got a "token". I thought "yay now I can get cards from a specific block I want, let's use it to play a Tempest draft."
No warning or anything, token used up, boo it costs 7000 to enter. Okay, I sold all my cards I'm not using in my decks and had at least 100 value. Sold my 4k beta serra angel and meekstone for 1k as well because...there is such a restriction. And used up all my winnings from the previous draft to enter. No choice, if I don't play the draft will disappear over time like all others before did. Then I almost won the first round, but game crashed, and next time I lost. My card pool was absolutely horrible. So I was left without money, and cards to sell...but I still had a good red deck to play.
And this is exactly where I still am, I haven't won much good red cards since then nor found much in the shop. I was able to upgrade a blaze to a fireball, a 2/1 first strike to a 2/2 double strike and such minor changes, but nothing big.
I see several major balance problems here (which is reasonable for a beta release but it should be improved in the future)
1. Card prices. Yes you are guaranteed a rare per win from the pack but they also sell for as much as a common, it's not helping. It's not making much money. So you earn like, 30-100 credits per win at best. I suppose the 1/5 sale price is also hurting this a lot.
2. Card prices again. Good cards, if they are rare, cost a fortune. I had to pass on an
Oblivion Stone because 2.9k was too much to pay. You can buy like 50 other good cards for that, even if you have the credits, but more realistically you won't. You earn that much in like, 40 games. And by that time AI is already at the highest level.
3. AI ramps up waaaaay too quickly. On "normal" difficulty, it plays hard decks before you can even unlock selling cards for their actual price if they are worth over 1k. I might change settings for this and start a new game, not sure. Don't like the idea of losing the cards I already earned and risking an even worse starting deck. I would expect to reach the hardest tier when I already unlocked a decent sale price and can afford buying stuff (including packs, or tournament entry) regularly. This is not the case, Hard AI triggered on game 30 something. ...I just looked at the game and there seems to be an "expert" tier above "hard". Now I' officially worried. In another 30 wins I need to produce mox lotus tier decks?
4. Pack prices. These are unreasonable. You get a pack free every win..but to buy one you have to spend like the winnings from 10 matches and that's the cheapest pack. Let's not talk about buying anything from an older edition, that's going to take forever.
...I had no idea you can play 40 cards in quest mode. That changes things a lot I guess? Feels weird to play 40 on a constructed format though. (Yes your card pool is limited, but not more than in real life. I mean, you have to buy cards in real life constructed too and you have to earn that money somewhere...so same deal as the game really except you don't earn the money by playing the game in the real world.)
Maybe these numbers work better in a smaller world, but in "all cards" it's pretty bad. Building any deck that has a deckent strategy usually requires 3-4 copies of several specific cards which most likely take hundreds or even thousands of wins.
Edit : reducing my decks size to 45 cards made games go much better. If I can keep an acceptable win rate after it ramps up to "extreme" I'll be happy. I'm still worried other players might not get this lucky. Red has inherent advantage over the AI because the AI can't consider direct damage you might use in the future when deciding on how to block or attack or play in general. It won't hesitate to tap out with blue when only one fireball away from losing and can't conserve hp either.