Two weeks ago, Somalian pirates unexpectedly leaked the Technical Preview of Office 2010, which will be released to testers in July.
Being an early (software) adopter, I just couldn't resist trying it... ;)

Office Professional Plus 2010 took around 8 mins to install on Windows 7.

Starting up any Office app takes only a few seconds, even on a cold start with the new 'spectrum' boot animation. The new boot animation has a cancel option to prevent you from opening the app if you have launched it accidentally.

The first thing you'll feel is that it's very very fast. Animations, menus, formatting options - everything is fluid, without any lag. Basically Office 2010 has been given the Windows 7 treatment, optimized to the hilt. Even memory usage is much lower.

A quick look at the interface shows no major change from Office 2007. The Ribbon (aka Fluent UI) is here to stay, albeit now with Aero blended in & an arrow button to hide it. Icons are no longer outlined, giving a sleeker Ribbon.

The Office button is no longer a menu, but a whole new page with the same standard options – New, Print, etc.

You'd probably be disoriented at first, especially with the new Print options.

Bored of the dull white skin? No worry, there'll definitely be more options in future releases including a matching blue Windows 7 theme.

This is probably one of the most important improvements of Office 2010. Office 2007 was much hated for its Ribbon that decreased productivity as compared to customized toolbars. Office 2003 users can now rejoice - Ribbons are now totally customizable! You can make your own custom tabs!

Security has been given prominence in Office 2010 with a 3-tier protection – DEP, Document Validation & Protected View.
Protected View kicks in when you open downloaded documents - it essentially opens it as read-only, with one more button to click to access editing.

With the lack of a change-log & the Help file being that of Office 2007, it's hard to identify all new features. So I just focused on new Word features. (A few more features are on beingmanan.com)

Insert Screenshots from opened windows in the background.

Artistic effects similar to Photoshop.

Remove background from picture! Great for removing simple gradients, but not recommended for detailed backgrounds.

Open Type Ligatures – whatever that means…

Powerpoint-styled Word Art can be applied to any piece of text.

The new Search sidebar

& finally Office 2010’s Feedback program – Send-a-Smile. :)

The Bottom Line
In all, a very fast Technical Preview, very much worthy of being a successor to Office 207. But it’s still very much incomplete – missing icons are replaced by a red dot! & it has bugs – I couldn’t make AutoConnect work on the Basic Electrical Template for Visio (it worked on my first try).
If you are thinking of downloading Office 2010, I would suggest you wait until the public betas because many leaked versions are being distributed with trojans, mostly botnets & mainly because this TP is a 30-day trial.