I started playing this after I got back from my holiday, it's fun to practice my decks with casual matches on my laptop while I'm watching shows.
Although, it's currently 4 in the morning here and I've been playing for about 10 hours. I haven't seen a creeping addiction this bad since... WoW... Go figure.
It was fun for about 2 weeks when I ran out of in-game gold and couldnt play the arena.
I don't seem to have a problem with this (although I've only played 3-4 arenas with a best streak of 4). I just Farm each daily quest and play casuals/ranked to work up the cash I need.
Theres little point to playing the "regular" matches without laying down cash on cards, because the other guy will always have a better deck.
I can see what you mean about being concerned about decks that are just better because of the greater cards, but I still managed to finish quests in about 5-6 matches by looking up some basic build decks and tweaking them with the expert set cards I'd acquired through arena to achieve the goal of the build better. When I was sure they were viable through some practice, I took it to casuals. Rinse, repeat.
You may hit a few walls with players using expert decks, but you're bound to run into circumstances that'll allow for easier wins if you keep at it. Right now I'm playing ranked matches with a decent mage deck and getting 2-3/1 win/loss just by playing smart.