Unlike Mobile Safari or even Opera Mini, Firefox Home is not a standalone web browser. You can navigate through bookmarks and opened tabs imported from your main computer (there's no navigation tree for history, which may be a blessing in disguise depending on your browsing habits). You can search for items in history, tabs, or bookmarks. Once you're on a webpage (which loads noticeably slower than Mobile Safari), you can perform all the usual functions -- scrolling, zooming, clicking links, moving back and forward in history, e-mailing and copying links -- that you can perform in almost any other app's in-app web browser. And that's really it. There's no URL field, which makes normal web browsing almost impossible; there's also no search field, no "tabs" like Mobile Safari, no way to edit bookmarks. As far as I can tell, the sync is one-way; nothing from my browsing on the iPhone showed up in history on my Mac's Firefox.
There's no doubt Mozilla could (and probably would) create a mobile version of Firefox for the iPhone if it was allowed to do so. Since Apple won't allow third-party browsers not based on WebKit, Firefox Home is about the best Mozilla can do. So if I knock Firefox Home for the features it doesn't have, it's not because I think Mozilla was stupid and "forgot" to put in an address bar or any of the other things a full-fledged browser has.
Still, is the app worth your time? That depends on how much you use Firefox on your main computer. If Firefox is open all the time as your main web browser, with several tabs open at once, and you have hundreds of bookmarks that, for whatever reason, you just don't feel like transferring to Safari, then Firefox Home may provide a necessary bridge between Firefox and Mobile Safari. If you're like me and Firefox is your second or even third choice of browser, then Firefox Home may be of limited utility. If any of you can think of uses for this app that I've overlooked, feel free to let us know in the comments.
I will give Firefox Home credit in one area. Thanks to its standardized page layout and text rendering, and its respect for the iPhone's native zoom gestures, Firefox Home is at least a better browsing experience than Opera Mini.