I did about 2-3 runs of the demo, all as Bob.  

Balance seemed good enough for now, but some cards definitely felt better than others.  Any card that caused a permanent stat change seemed like a much better choice than ones that cause a temporary change.  Post battle, it almost always felt necessary to pick the heal over the other options.  Maybe a few cards that provide some kind of healing can help with that?  Money is spent too fast and picking a random card felt too risky, as you may get ones you don't need.

The different factions didn't really feel all that different.  Possibly because I didn't see many of the higher rarity cards, but the lack of faction-only mechanics and lack of visual marking made the various factions blend together.  The faction skills didn't seem to be too useful due to the fact that several of them rely on random chance, and the interface for using them was not very clear. 

The game's various UI elements seemed a bit too small on my screen (13", 1280x720 I believe) which made it difficult to read information on the cards, even on mouse over.  The interface also felt like it could use more information, something that would be helped by having tooltips.  The non-placeholder graphics looked nice, and I can see a unique and pleasing art style developing so far.  A particularly nice touch is when all the card interactions are shown at the end of your turn, and a "slow" option for it would be really nice.

The biggest issues so far are the lack of goal overall (although I'm guessing this is just due to the fact that it is just an alpha, but more importantly I think the game would benefit from letting the player have more interaction in the battles.  Being able to swap 2 cards is a good start but I personally think both characters should have at least 1 player chosen way to alter the board each turn, on top of their ability.  This may not be the type of game that focuses on mid-battle strategy though, in which case it probably is fine as-is.

The game overall is coming along really well.  Despite my nitpicking I actually liked the game and I think that with more work it would make for a very addicting and fun game.  I can see myself paying $15 for this once it is finished and polished up.  I'm definitely interested in what this game is going, keep us updated on how it progresses!