Well, there's a bunch of suggestions.
The first one would be to create a ladder and some kind of "World ranking" under several parameters.
"Won games number"
"Number of played games"
Second one wold be to add 15 minutes of game time, as 10 minutes sometimes is small when and 30 minutes is too long.
I often choose a game in the "Find game" section and also create a new one (with the expansions I like, etc). The problem is that when someone accepts my game there is no visual feedback while playing so I constantly have to check the "Game list".
If somewhat, the "Next game" function can be extended to accept this games wold be perfect.
Also, It would be lovely to have some kind of "random match" that pairs you with a same level person with random expansion sets.
And... I think that's all.
Oh, yes, one more thing...
Congratulations for this amazing game It's as easy to play as the real card game.