There have been several large patches since release, you have a lot of downloading still to do.
In general the patching goes as follows......

Download a bit, Patch/apply that download, download a bit more, patch/apply that bit and so on

You may or may not get to play today depending on your DL speed (and what time it is-heh heh.) At least you aren't trying to do it with everyone else.

The game is a total of 36 GiB in size, including voiceover files (5.7 GiB).
Most of these files have been changed since launch or totally new ones have been added so it has to download the bulk.

Note that voiceovers are downloaded in a seperate step after them main client and have a seperate progress bar for repair scans and the like.
Also they are not partitioned in any way (4 really big files), so if they do any changes that is always a big download (they only do changes there during content patches, however).
Average patchsize is under 100 MiB, with only first install and content patches having any real size.

Note that the bulk are just data files that seem to be identical between NA & EU client, as well as Mac and PC version (asuming same patch state).
So if you ever need anotehr client, you can speed it up considerably using this technique:
http://www.esoui.com/forums/showthread.php?t=1874

[Moderator Note: Edited and added "http://" to the post, fixing the link.]

What technique!? Your link takes you back to this post