When I got my first Android "smart phone" it felt like a slow, hard-to-use computer on dial-up Internet. Now I use an Android G2 (HTC Vision) which I'd call a pretty snappy, easier-to-use computer. I can't say I do much on it besides calls, texting, and Twitter but I'm excited that Firefox Mobile has just been released. You'll need a newer Android phone (arm v7) to install it and it's going to eat up a whopping 14MB (plus caching) but, hey, Firefox is now mobile!
Here's a sweet video about it.
I've been using the development version for a while (nicknamed Fennec) and here are some things I like about it. First, it's 2-3 times faster than the default Android browser. Most importantly though, Firefox Mobile syncs seamlessly with Firefox 4 desktop; you can access all your bookmarks, your Awesome Bar history, and you can view open tabs on other devices. Every action on a mobile device should require minimum touches and minimum typing. Keeping two computers in sync like this makes a lot of tasks way easier. For example, before I take the train I usually open up some maps or articles on my desktop so that I have them on my phone. One interesting point about synchronization is that all data is encrypted before it gets sent to Mozilla's servers. This means no one but you has access to it (more cloud services really should adopt this local encryption pattern).
The power of Firefox has always been its outstanding community of developers who build addons to customize the browser. There is an addon for pretty much anything you can think of and there are usually more than one to choose from. As you can imagine, this same community has been hard at work on Firefox Mobile; check out all these shiny addons! Just like desktop, you probably won't ever use most of them but you're bound to find one that you can't live without. The exciting part is that Firefox Mobile is pretty easy to extend so if there's something you wish you could do on your phone, it might make sense to create a mobile addon for it.
The reality of software is that people don't just want to use it, they want to make it better. Really, they do. A plugin / extension framework isn't just handy for implementing essential features, it also provides a quick way to experiment with new interfaces. You might have a really good idea for something but you'll never know if it's truly great until you build it and try it out.