The contact sync is fine if you know how to use it. Unfortunately, this information isn't spelled out in any official FAQ that I know of.
Originally Posted by E92Vancouver
People find that postal addresses that they have in their BB get truncated after sync with Google. There is no "fix" but there's an easy workaround: Ignore the city and state/province fields in the BB Address app. Put the entire postal address in the "Address 1" field and you'll be okay. Google treats addresses as single blocks of text, and fails to handle separate fields properly, so this is the only way to keep Google happy.
Gmail sync is one-way. Mail deleted from the web server will not be deleted from the phone in Gmail. Yahoo mail does it, but not Gmail; I don't know why.