I have had mine since release day.
The phone itself has been great.
My only real gripe(s) have been when I somehow downloaded an app that contained a worm that slipped past the virus protection.
That forced me to do a Factory Reset to get rid of the worm bot.
Then my next gripe was that Kies 3.0 did not totally do an image restore. That is, it did not restore my home pages nor the folders..... It did restore the data for the WiFi and networks, and it replaced all of the apps.
but, it takes hours to rebuild the look and feel of a phone the way we like it.
I am trying out Helium right now to see if it will do a total restore. I have a few backups made with it, but have not been brave enough to do a Factory Reset and hopefully have Helium do a total restoration.
One day, I will take the plunge and root the phone.