I erased all my contacts in my Samsung S i9000 to import all of them from Google. Sync has downloaded only around a half of 4500 contacts. Over and over syncing to get the rest of them I get an error 'Sync is currently experiencing problems...'. Sync Gmail and Sync Calendar work well.
After some troubled tries I could save (not sync) all my contacts. First try was to remove all contacts again and sync with Mac address book (which is also synced with Google) using Kies (Samsung); it always crashed when around 80% sync task was performed. Then I remove all contacts again, created a vcf file containing all Address Book data, copied it to the phone and finally imported data from file.
Just to check sync with Google I added a test contact to Address Book, synced to google and then synced from the phone. The contact was added despite 'Sync is currently experiencing problems...' was displayed again.