Maintenance for the week of December 22:
• NA megaservers for maintenance – December 22, 4:00AM EST (9:00 UTC) - 8:00AM EST (13:00 UTC)
• EU megaservers for maintenance – December 22, 4:00AM EST (9:00 UTC) - 8:00AM EST (13:00 UTC)
If you are just updating your game, use the launcher. The only reason to use Steam is to change the drive upon which ESO is installed. If you use Steam right now, you're going to download twice. Like I did.