GreenBrowser is one of a surprisingly large set of browsers which aren't called "Internet Explorer", "Firefox," or "Opera." Occupying a very thin slice of market share, many are simple Mozilla clones or partially-complete proofs-of-concept. Remarkably, freebie GreenBrowser seems to be a complete, well-supported browser with a lot of useful features.
The real issue with browsers is, a Web page is a Web page. Either a browser shows every Web page properly, which makes one as good as the next, or it doesn't, which makes it useless. This means browsers must compete entirely on features besides the most important feature, which is, rendering Web pages. How does GreenBrowser do?
Some alternative browsers, such as Google's Chrome, go for simplicity--get everything out of the way but the page itself. GreenBrowser isn't in that category. It offers a lot of tools for tab management, more than I've seen on any browser which hasn't be stuffed full of plugins. You can, for example, lock a tab--password protecting it so that a curious coworker can't click on it and bring it up. You can close all tabs with a single base URL (for example, the dozen tabs you opened while playing link hopscotch in Wikipedia) with a single click, while keeping all other tabs open. You can save and load groups of tabs. GreenBrowser also has your bookmarks in a sidebar, Firefox-style, which is a feature I now refuse to live without. (Sorry, Chrome.)
There are some annoyances. I found it seemed slower to render than Firefox, my browser of choice, albeit not by much. There is a very annoying green "G" icon which floats over every page until you finally figure out you can make it go away by clicking on it and choosing "Hide Monitor., which removes it permanently unless you choose to show it again. Greenbrowser's Web site is an adequate, though still fractured, translation of a linked Chinese page. The program includes the expected translation flaws, though they are not as bad as some I have seen. There is no close button on the individual tabs, so you have to right-click and choose a menu item to remove a tab. (On the plus side, there's a feature to re-open a recently closed tab, something which is always useful and needed!)
Should you use GreenBrowser? Well, it's free, so there's no harm in checking it out. Whether its plethora of tab-handling and navigation features are enough to make it replace your current browser of choice is something only you can find out. If you do a lot of multitasking in your browser, it is at least worth a quick look.