I have been using Internet Explorer 8 (IE8) almost exclusively since the first Beta became available. Now, my primary OS is the Windows 7 Beta, so IE8 is built-in as my default browser. I have run into my share of page compatibility issues. The most notable for me- which has since been addressed by Microsoft, Google, or both- was that Google Maps just flat out did not work in native IE8 or in compatible mode. I guess that should have been a red flag clue that IE8 compatibility mode does not equal IE7. Obviously there are still things that are different between IE7 and IE8 compatibility mode or any site that worked in IE7 would work the same in compatibility mode.
Now that it is in Release Candidate (RC) mode, with an official release rumored to be on the imminent horizon, most of those types of issues have been resolved. However, there are still issues created by changes made by Microsoft in IE8. Web developers who have developed their sites to work in IE7, Firefox, Opera, Safari, or whatever else may very well have to modify the underlying code in order to make it work in IE8- even in compatibility mode.
To Microsoft's credit, the IE8 team posted a detailed breakdown comparing IE8 compatibility mode to IE7, and comparing IE8 standard mode to IE8 compatibility mode along with code descriptions of the issues and suggestions or recommendations for how to modify code to make it work or workarounds to make sites functional in IE8. Judging from the comments in response to the post, the reaction is quite mixed. Some praised Microsoft for the improvements they have made and for writing this post to help developers embrace the changes, while many attacked Microsoft for not simply playing by the same rules that seem to be working just fine for every other browser, as well as for taking so long to develop and release new versions.
