Before Microsoft announced that Internet Explorer 5.2.3 would be the last OS X version, the venerable winner of 1990's browser war was already showing its age. Microsoft hasn't produced a major upgrade in years, and IE now lacks must-have features that are common in other browsers. For instance, IE is the only Mac browser without the capability to block pop-up windows. It also doesn't support tabbed browsing, the ability to have multiple Web pages open in a single window.
IE has also fallen behind in its support of Mac OS X features. (Microsoft says it hasn't gotten sufficient access to the OS itself over the years.) For instance, IE uses its own (perfectly adequate) security settings instead of using Mac OS X's Keychain feature as Camino and Safari do. (The Keychain Access utility is a handy single location for editing all passwords used on the Mac, including user logins, local servers, and Web sites.) We like IE's high degree of configurability, but finding what you need in the confusing Preferences dialog is mostly a matter of trial and error.
Internet Explorer is reliable, but its features and performance are falling behind those of the newer browsers.
IE has also fallen behind on the performance curve. Safari, Camino, and even Opera are all faster in rendering pages and more responsive with resizing screens.
IE is still a free download from Microsoft, and it's well supported. The browser includes extensive online help, and Microsoft provides online tips and FAQs.