I think how the wallet is managed is one of the major problem of the bitcoin client as now. To use it you have to have it unencrypted and this is a serious security flaw as it allow a virus to directly steal it. I know it has been asked a lot of times but, we need a client that can use a CRYPTED wallet.dat

Then we have the fact that well the client automatically create wallet.dat in his folder inside roaming without telling you anything and while it is not a problem for people who know how the software work, it's a bit fail for new ppl, because by trying the bitcoin client you just end with a NEW folder under roaming that you don't even know it exist (you discover it LATER, when you go read the wiki). Not exactly the safer way, there should be like something in the client that allow you to create the wallet and place it where you want or something like that...