Matchmaking is completely broken. Either I get a match where I'm a solid 300 power ahead of my opponent and I steamroll them, or I'm 500 power behind my opponent, and it's not uncommon for me to not even get a single turn before I'm wiped.
Considering that Arena is the only thing you can do in this game on an unlimited basis per day, you think there would be a little more effort placed into making sure it's not a repulsive experience. The fact that there's really only one viable F2P team, and if you see Dash or Zurg on the other side of the board, you may as well just hit the auto to get things over with as soon as possible is disgusting.
I realize the game is young, but this is the type of thing that chokes a game out. I don't invest a whole lot, if any money when I first start playing, because what is given to the F2P players is indicative of how interested the devs are at making a game that is sustainable in the long term, or just getting a quick cash grab. Right now, my gut is that this looks like a quick cash grab, which is a shame, because there's a fun game here.
I guess in the end, ultimately, the Arena needs to be tightened up in terms of matchmaking, a serious rebalance of characters needs to happen so there's some semblance of being able to use a variety of teams, and F2P folks need to at least have a fair shot at getting characters. Yes, in the short term, it does mean that you might not make as much money, but you grow a player base who would be willing to spend some money, which more than makes up for a rapidly dwindling player base alienated by being asked to fork over triple digits each week to get the newest character.