Opera 10.5 pre-alpha has been released today with an enhanced support for CSS3 and HTML5 along with almost an exponential increase in JS engine performance. So much for 
one update. Besides these and some more technical enhancements, there has been significant improvement in the User Experience too especially for Windows 7. The new Opera 10.5 has made an extensive use of the Arrow glass effect. What else? It supports Private Browsing.
Unlike Firefox where you have to close down previous window to open a private browsing window, here you can simply open a private ‘tab’ while browsing. No cookies saved, no track recorded. Here’s a quick comparison of how it works in Firefox and the new Opera 10.5
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Notice that in Opera, you can open a private tab and your previous ‘public’ tabs are still open whereas in Firefox, the moment you click ‘Private Browsing’ all the tabs are closed and a new window is opened.
Besides this, there have been a lot more improvements like the tab bar with the glass effect and it’s also expandable, see this:
Now see how you can elongate the tabs to get thumbnail preview of the pages:
And the new footer bar sports some great features too:
The first button from left is the Link Synchronization which actually synchronizes links across multiple devices/computers in your home.
The second button is “Turbo”. You can reduce the load time of the pages by enabling the “Turbo” which actually compresses the images and other multimedia while transferring. It might result in reduced graphic quality but it comes in handy where you can compromise in quality for speed aka dial-up-connections .
The third button (on the right side) fits the browser window to the screen size and the fourth button hides/shows the images in a page which the last dropdown menu is Zoom in/out.
Even though the updates have been great but it crashed two times while I was reviewing it so there is still no final verdict on stability.