I really miss having the Vs AI mode that Duels had. People just suck sometimes (emote spamming, roping, endless tier 1 opponents) and sometimes a man just wants to play jank against Razorfoot Griffins you know? Also I don't find the graphics much better if at all than Duels. I wish I could at least make it a more dark/gloomy background/theme.
I miss having the option to play on against AI. Sometimes people bail way too early or when your playing a combo deck, you want to practise the end game...
I'd say the game is enjoyable ATM. The main problems in terms of meta are in common with all of standard, so it's not really arena's fault.
I haven't played much, but it's from a lack of gaming time, not due to not enjoying the game.