The zero tx fee makes for a quite user-unfriendly experience — it means that some of your transactions will require more than a hour to complete, because the client won't suggest a fee for them (e.g. for a 0.3 BTC transfer) — that is, until you don't go into Settings and set a default tx fee manually.
There at least should be a warning that transaction is being sent with a zero fee and will take a very long time to complete.
OS: Mac 10.7.5 Client: v0.8.5-beta
