The big problem I see with BitCoin is that everyone's entire transaction history is public. So if you ever use BitCoins to buy something that needs to be mailed to you, or trade them for money sent to your bank, your anonymity is basically gone—anyone who can coerce/subpoena/spy on the "real life" side of a single transaction can link your real identity to any transaction you've ever made or will make.
No, the convention and the default is to use a new receiving address for each inbound transaction, so this exposes only a small portion of your transaction history, not the whole thing.
Tangential, but a subject of some local interest:
Why Bitcoin will fail by Avery Pennarun. "The sky isn't red." Thesis:
I'm not sure I buy these and am not competent to evaluate his claims on 3., but would like others' critique.
L019: Bitcoin P2P Currency: The Most Dangerous Project We've Ever Seen by Jason Calacanis. A rather more enthusiastic viewpoint of the project:
The actual text contains many more caveats than the eye-catching selection of points above.