I've installed it on my Nexus One, and what I have to tell you is that: in normal browsing, Android's default browser is quite at the same level with this browser, but if you need to play Flash on your phone, Skyfire beats anything. Flash content is not automatically played, as you have to go in menu and select "video". A new window will open, playing the requested video.
The advantage of this is that you don't need a modified rom in order to try playing Flash (I'm not sure if it can be done like this), which is done by rooting your phone, which will void your warranty. But with Skyfire, you can enjoy Flash (and other scripts that Android's browser isn't capable of running), risk-free.