During our brief hands on with the Skyfire mobile browser at CTIA, it actually lived up to most of its claims, and we walked away fairly impressed. We saw it on two different devices, though most of our time was on a Sprint HTC Mogul. Besides rendering media-heavy Giz with surprising snap (a feat that made the Instinct's browser cry), it churned out YouTube and Hulu videos like a champ. Zooming isn't quite as intuitive as Safari—you touch, a box pops up which you can drag around, then you touch again—but I was told they're working on making it more natural. Overall, it's definitely one for Windows Mobile users to watch, and we'll be getting some more time with it soon.
I've been running the beta for the last few weeks, and I'm very impressed. It's very smooth, the video/audio playback's amazing, and it overall just covers my needs very well. Needs a bit of stability work and multi-line text input support, as well as an improved startup time, but overall it's very strong.