One of the problems I have with Android phones is that by default (?) the configuration is trying to sync the phone with my Google account. For my case, it tries to download (sync) my emails (gmails) and photos I uploaded to picasa. This is a disaster since I have lots - say more than 10,000 emails - and Gigabytes of photos.
I found out about this a while ago when I tried a new Android phone. I noticed that there were some networking activities. Apparently, it tried to sync my photos. I think it did that when I am connected to WiFi, but not when I am connected with 3G. Had it also done the same thing using my 3G connection, my quota would be long gone. (Long time ago, I had similar problems but could not recall what.)
Some people love the idea of synchronizing contacts on the Android phone with their gmail accounts. I don't. If I do that, than thousands of my contacts would be on my phone. Searching for a contact in my phone would be a nightmare.
Other than taking my networking quota, I am also worried about privacy. What if I lost my phone? The person who found the phone could read my emails and downloaded my photos. Scary.
I think, by deafult Android should not sync data with Google accounts. Another option would be to create a dummy Google account for my phones. This is under my control. I should do this, then.