Biggest problem for this deck is big creatures...if you're up against gravity, you're in LOTS of trouble...fire, lots of trouble (since they get a lot of damage in before you can kill all the creatures). The only thing you have to combat this is Afla and Plague, which are not very good to use as a major kill strategy - Plague is too slow, and Afla is too expensive. Bone Wall is good, but what happens when you run out of bones and/or kill cards?
Edit: Also, your only offense comes from Bone/Graveyard and Condor...if either of these is messed with, you're in trouble as well.
Not sure if this helps, I know the idea is to get lots of cells on their side, then Bone Wall and Plague, but you will run out, and once you Bone Wall you don't want any more Cells out there, which means Plague is your ONLY source of creature control. Plus, this is a relatively slow deck, which means you have to worry about Perm control as well.