I haven't transferred my content yet but I assume Kies works great (used it for previous devices).
As far as Smart Switch, don't you have to have your old and new device at the same time in order to restore to the new phone? I'm asking because I'm selling my Note 3 before I pick up my Note 4.
I did all my contacts, calendar stuff , etc. etc. with my Google account. As for apps I did it manually since I wanted to "clean house" on some old apps that I wasn't using much .
The biggest problem I had transferring over was my apps....and I mean app with all the data!!
It seems Android sorta lacks when it comes to App transfer...Yes there are a bunch of options out there for rooted users, I was non rooted so there weren't much...And the ones tht did exist, I had to pay for a "pro" version which would do transfer app data.