I just synced my phone book. I can see it would be useful if I don't have my blackberry and/or laptop with me and I need to get some information of my contact.

However, it seems they missed a key feature:

Delete all contacts

right now, If i need to delete all my contacts, I would have to delete them one at a time.

Additionally, I am not sure if it is a both-ways sync or one way sync; or I can set up my blackberry to overwrite the content in the website. I would want to be able to control what should be synced and what shouldn't.