Opera has mouse gesturing, tabs, a speed dial feature which can hold nine commonly accessed web pages on the main startup screen when the browser launches (if a homepage is not set), the ability to move back and forth with cached web pages, rather than requesting a full page refresh, the ability to mimic or report itself as being Firefox, IE, or other browsers, and several other features which make it a desirable alternate choice.
Opera is a free download and works with Windows, Linux, Mac OS X, Solaris SPARC and Intel, QNX, OS/2, Linux SPARC, PowerPC and i386, FreeBSD i386 and BeOS. Version 9.25 is the latest stable release. Opera also releases future versions which are still under development. The current "preview release", as Opera calls it, is version 9.50b.
Opera also has several other mini-browsers, called Opera Mobile and Opera Mini for portable PDAs and cell phones. Opera Mobile is a full featured browser, and Opera Mini is a basic browser with many features disabled, but with a much smaller memory footprint. Opera releases regular updates to their browser, about one every two months.
Opera’s 9.25 changelog indicates the following fixes/enhancements:
1) Fixed an issue where plug-ins could be used to allow cross domain scripting.
2) Fixed an issue with TLS certificates that could be used to execute arbitrary code.
3) Rich text editing can no longer be used to allow cross domain scripting.
4) Prevented bitmaps from revealing random data from memory.
5) Fixed a problem where malformed BMP files could cause Opera to temporarily freeze.
Read more ... Opera main page.
In my experience from reading user’s comments about Opera over the years, many users who migrate from Firefox or Internet Explorer have some initial difficulties in adapting to Opera. I have used Opera exclusively ever since Dean Kent of RealWorldTechnologies mentioned that it was the only browser he used several versions ago (probably Opera 7). I have found it to be robust and it does nearly everything I need it to. There are still some web pages which Opera has a problem with, and for those I use Firefox or if I’m running Windows XP under Ubuntu Linux via VMware Server (which is all free, save the WinXP license), then I run IE6.
If anyone has not given Opera a chance, I recommend you spend a week with it. It has a really nice feature called "sessions", which allows you to save all open tabs exactly as they are. When you load Opera the next time you can resume your browsing session exactly as you were, with page histories in tact for each tab, etc. Quite a slick feature.