...

1)  Block size.  Satoshi could have probably anticipated this, and he (or the team) should have written some code allowing an easy expansion through time...  Whatever developers "win" the block size tangle, please think ahead guys!

2)  Limited acceptance by merchants (the principal thing retarding BTC growth IMO).  I do not know how to fix this one.  Time and customer demand?


EDIT:

3)  It is HARD to buy Bitcoin, especially quietly.