Contrary to what I thought, all the problems brought in by Sync 0.5.9 are still back.
The address book is still botched on the device, there are entries with no information present whatsoever (though I checked them before doing the sync, and they appeared to be fine after the sync).
Sync doesn't appear to honor the "sync manually" option and is doing something in background, destroying address book entries in the process.
Most ridiculous is that the problems with 0.5.9 were never offically acknowledged, and 0.5.11 never officially announced. Tsk-tsk-tsk.