I just upgraded all the Wordpress blogsites that I'm managing in our web host without any glitch at all. Thanks to Wordpress for making it seamless and of course to our internal upgrade scripts that backup files and database automatically, in case something went wrong you can always go back to the old version.

This is the advantage of hosting with us, we take care of everything including upgrading your Wordpress to the latest and the greatest release.

For others, here are the things you should consider before upgrading to Wordpress 2.1:

• Not all of your present plugins and maybe some of your theme functionalities will not work perfectly with Wordpress 2.1 so you better check it first thoroughly.
• One of my friend yesterday IM me and asked for help, he said after upgrading to 2.1 “no post is showing” in his site. I asked him immediately without thinking a second, if he runs the upgrade script? He said, what upgrade script? This is the reason, you should run wp-admin/upgrade.php in your browser. There are some database schema changes in 2.1 and upgrade.php do it all for you.

These only two I can think as of now. Anything I missed you can post it here via comment so that we can warn other Wordpress users planning to upgrade to 2.1.

Why you need to upgrade to Wordpress 2.1?
There are some attractive new features in this version.

• Autosave makes sure you never lose a post again. How I wish Drupal has this one too.
• New tabbed editor allows you to switch between WYSIWYG and code editing instantly while writing a post. This is cool, as this is mostly what my wife is complaining to me - formatting her post and most of time using WYSIWYG breaks her posts.
• The lossless XML import and export makes it easy for you to move your content between WordPress blogs. This is helpful to me as I usually move blogs from one place to another.
• Completely redone visual editor also now includes spell checking. Although this is already built-in with Firefox, still another good addition specially if you are still using IE. Not applicable to us, as three of our computers in the house are all now running Linux.
• New search engine privacy option allows you take you to indicate your blog shouldn’t ping or be indexed by search engines like Google. Well, I don't find much use of this feature personally. If you want to make your blog private, make it completely not accessible to the public; while if you want to publish it to the public, let the search engine crawl it. I don't agree anything in between :)
• You can set any “page” to be the front page of your site, and put the latest posts somewhere else, making it much easier to use WordPress as a content management system. I know this is only giving flexibility to other users that want to bend Wordpress to behave like other CMS, but I hope Wordpress will not try to accommodate more request of extending its functionalities in order to compete with other CMS like Drupal, Joomla, Xaraya or Typo3. Wordpress is widely known right now as perfect blogging platform - they should keep it and stay with it.
• Much more efficient database code, faster than previous versions.
• Links in your blogroll now support sub-categories and you can add categories on the fly.
• Redesigned login screen from the Shuttle project.
• More AJAX to make custom fields, moderation, deletions, and more all faster. My favorite is the comments page, which new lets you approve or unapproved things instantly.
• Pages can now be drafts, or private. Nice!
• Admin has been refreshed to load faster and be more visually consistent.
• The dashboard now instantly and brings RSS feeds asynchronously in the background.
• Comment feeds now include all the comments, not just the last 10.
• Better internationalization and support for right-to-left languages.
• The upload manager lets you easily manage all your uploads pictures, video, and audio. Yeah, I saw this feature works, and really good especially if you intend to post same image as you posted before.
• A new version of the Akismet plugin is bundled.

Enough good reasons to upgrade to Wordpress 2.1 huh?