The biggest improvement for me was that FTM 2014 finally lets me globally order children by age, something that required awful contortions before that fix.
I have two main trees - one for me and one for my wife. Sadly, I only tested my own tree during beta-testing FTM 2014 and I had no syncing problems, but once I started with her tree, it has been a nightmare.
The problems with syncing for me were only for uploading changes in the tree from FTM 2014 to Ancestry.com. It always downloaded like a charm. The workaround was to make a few changes, upload them, and if that broke to delete the local tree and redownload it. Ugly but it worked.
My current fix - I took a GEDCOM, imported it into RootsMagic 6 which flags errors, corrected the glaring errors on the online tree, and synced. It seems to be working much better now.
I think that what FTM needs is a utility to ID problems with the tree so you can correct the tree.