Firefox is in a state of rapid updates, when it seems every month brings a new version to your screen. In the vast rush to get new features out there, older features, perhaps considered no longer necessary, are dropped by the wayside. Fortunately, the extremely robust plug-in ecosystem and developer community that keeps Firefox my personal browser of choice (winning me back from Opera solely due to some add-ons I found I couldn't live without) means that if there's a feature you like, someone will add it back in if it's gone. Thus it is with Status-4-Evar, which recreates the pre-Firefox 4 status bar widgets, but with improved flexibility.
The trend in browsers today is towards a minimalist and Spartan interface, which makes sense for the tiny screens of netbooks. This is why many of the features included in Status-4-Evar went away. I've got a widescreen monitor at a desktop PC, though, so I have a lot of real estate that's not doing anything. Status-4-Evar brings back Firefox's thermometer bar of yore, which shows how much of the page has loaded, a download progress icon, and a text status bar. All of these have several configuration options, including placement in various toolbars, color, and other types of general behavior. For example, I have set page load status to show as both a small bar on the bottom of my screen, and as a field of color that creeps along my address bar. You are not required to do both, but you can, and flexibility is Status-4-Evar's goal. (Spelling, clearly, is not.)
If you don't want more things on your screen, of course, you won't want Status-4-Evar. If you do want this information, Status-4-Evar gives you an easy way to see it. Overall, I find it interesting but not vital; I didn't notice most of these features were gone until Status-4-Evar brought them back. If I have any complaint about Status-4-Evar's functionality, it's that it's not always entirely intuitive what an option might do or what to set to get the effect you want, but this is an issue easily solved with a few minutes of fiddling, or quick trip to the support forums.
Last thought: There's the usual issue that no matter how few resources any given add-on may consume, the sum total of multiple small add-ons can be a cumulative drag on performance. iIt's always good to consider the cost of each straw you add to the back of the Firefox camel.
Note: Clicking the Download Now button takes you to the Firefox add-ons page, where you can download Status-4-Evar into your browser.