Upgraded to 1.9.0 using Outlook 2010 and get an error when syncing all Outlook folders ("Loading items for Outlook failed"). In Settings > Sync > Contacts, Events/Tasks, and Notes > Advanced > Outlook Folder to Synchronize, it shows one long string of numbers and letters.
I re-installed v1.8.15 and syncing is now working again. Where it showed the long strings it all looks correct again (Contacts, Calendar, etc.).
I have a similar but different problem, and I too had to switch back to th previous version. For privacy, on the phone side I'm using the local contacts, local calendar and notes to be synced with outlook local ones.
Now local phone data are no more an option for sincying....