Prior to v0.4.2?: Mostly works but there's a few bugs (then again the better performance may have just been a result of a smaller database back then)
v0.4.x and v0.5.x: There's lots of bugs and it's very slow, I rarely use it as a result (actually I would have preferred the poll option: The client's a POS, and I'm not talking about Proof of Stake
v0.6.x: Mostly works but there's a few bugs (at least so far)
It was mostly the wallet scanning optimization fix that made things better.
I still think there is a performance bug (/ maybe memory leak) in the blockchain syncing code, but it seems to only be a problem when syncing the blockchain after being offline for a while. So I can work around the issue.