Windows 8.1 update 1

You can do it manually, but the update is actually 6 separate updates (some of which you may have already received as part of regular background updates).

For the best experience, I'd recommend just waiting another few hours.  The update server will begin sending them sometime today.

Windows 8.1 Update direct download links:

For Windows 8.1 x86: (32-bit Windows)

KB2919355
KB2919442
KB2932046
KB2937592
KB2938439
KB2949621-v2 (for Server 2012 R2 only)

For Windows 8.1 x64: (64-bit Windows)

KB2919355
KB2919442
KB2932046
KB2937592
KB2938439
KB2949621-v2 (for Server 2012 R2 only)

Microsoft recommends you install all updates (see how to install Windows 8.1 Update) in the following order to avoid issues. Always reboot when prompted (don't skip a requested reboot between updates, you'll cause big problems!)

1.  KB2919442
2.  KB2919355
3.  KB2932046
4.  KB2937592
5.  KB2938439
6.  KB2949621

Run Windows Update periodically (not the MS Store) to get Update 1 installed. I'd try again about every 10 minutes (best guess now is 1:00PM US EDT).  This is a large update so be prepared for it to take anywhere from 20 minutes to more than an hour. Also everybody and his brother will all be trying to download and install the update (Got to have it now effect) which will load down the servers and make things even worse.

If you don't want to wait for Update 1 to become available on Windows Update
then read the following about installing the update (KB2919355) manually.
http://www.microsoft.com/en-us/download/details.aspx?id=42327&WT.mc_id=rss_security_updates

Install Instructions
To start the download, click the Download button and then do one of the following,
or select another language from Change Language and then click Change.
Click Run to start the installation immediately.
Click Save to copy the download to your computer for installation at a later time.
 
      
These KB's must be installed in the following order:
KB2919442, KB2919355, KB2932046, KB2937592, KB2938439, and KB2934018.
KB2919442 is a prerequisite for Windows 8.1 Update and should be installed before attempting to install KB2919355

As always for your protection create an Image Backup to an external USB drive before you start.

EaseUS Todo Backup Home V6.5 http://www.todo-backup.com/
Free version: http://www.todo-backup.com/products/home/free-backup-software-features.htm
Includes: Incremental backup, Disk/partition clone
User's Guide: http://www.todo-backup.com/download/docs/User_Guide.pdf
(Note: Install Todo and then create an "Emergency Disk" before you start creating your first image backup)
Version 6.5 supports XP, Vista, Windows 7, 8 and 8.1

Acronis True Image 2014 - has a 30 day trial version available, trial Key send via Email.
Note: Cloning and drive initialization (creating a MBR) are not supported in the trial version.
For the trial version, only recovering is available when booting from an Acronis Bootable Media.
Install Acronis and then create a bootable Restore/Rescue Media CD before you start creating your first image backup
http://www.acronis.com/homecomputing/products/
30 day trial : http://www.acronis.com/homecomputing/products/#tryorbuy
True Image User Guides and documentation:
http://www.acronis.com/support/documentation/
2014 supports XP, Vista, Windows 7 and Windows 8

J W Stuart: http://www.pagestart.com

If you wait two or three weeks to install new updates, you’ll be
able to draw on the experiences of millions of testers. 

`~`

The current time and date right now in California, United States is  10:08 AM 
 Tuesday, April 8, 2014
 Pacific Daylight Time (PDT) -0700 UTC

UTC/GMT is 17:08 on Tuesday, April 8, 2014

 Current Weather Conditions in Los Angeles

Fair   74°F / 23°C

The update is now available (KB291355) on Windows Update.

J W Stuart: http://www.pagestart.com

The update is now available (KB291355) on Windows Update.

J W Stuart: http://www.pagestart.com

Finally got the update KB2919355 to India on 9-4-2014 at 00:00

Update has installed successfully but unable to open the few apps. All my Metro apps is not working, even Mail-Calendar-Messaging-People. All Metro apps just crashed at the splash screen and went back to the desktop. 

I am able to open the Store but when i try to install any apps then i get 0x80070002 error

can anyone help me with this problem

I may have an issue, & I feel really stupid for this... I went to the Download Center & downloaded & installed the update files. I didn't read the instructions before I installed... I saw that they must be installed in a particular order: KB2919442, KB2919355, KB2932046, KB2937592, KB2938439, and KB2934018.

#1: The file list it gave me to download did not include KB2919442. It said that this must be installed first.

#2: I installed them in the order they downloaded: KB2937592, KB2934018, KB2938439, KB2932046, KB2919355

I am now afraid to reboot my computer. What do I do?

I may have an issue, & I feel really stupid for this... I went to the Download Center & downloaded & installed the update files. I didn't read the instructions before I installed... I saw that they must be installed in a particular order: KB2919442, KB2919355, KB2932046, KB2937592, KB2938439, and KB2934018.

#1: The file list it gave me to download did not include KB2919442. It said that this must be installed first.

#2: I installed them in the order they downloaded: KB2937592, KB2934018, KB2938439, KB2932046, KB2919355

I am now afraid to reboot my computer. What do I do?

is it possible to uninstall those manually downloaded files from your pc?

or

do the system restore.

then install KB2919355 from windows update. Scan ur computer and windows update will show this KB2919355

Thank you for your help. I tried to do a restore, but when it restarted, it installed the updates. So the restore failed. But, fortunately as far as I can tell, everything is as it should be with the new update, & everything works.

1st impression, don't like the integration of apps into the desktop, but I'll get used to it. Maybe with Windows 9 they'll finally eliminate the desktop completely & integrate all the functionality into the new system. :-)

You don't have to get used to it, it's your option.  Right-click your Taskbar and go to Properties to decide how that works.  You can say "Show Windows Store [modern/metro] apps on the taskbar" or not.