Mozilla Gran Paradiso Alpha 4 Out

Mozilla has a new alpha of the next major release of Firefox (i.e. 3.x) available for download.  As with all alphas and betas, this is not a finished product, so don't disregard the final product based on what you see in the alpha.
"Gran Paradiso Alpha 4 is an early developer milestone for the next major version of Firefox that is being built on top of the next generation of Mozilla's layout engine, Gecko 1.9. Gran Paradiso Alpha 4 is being made available for testing purposes only, and is intended for web application developers and our testing community. Current users of Mozilla Firefox should not use Gran Paradiso Alpha 4"
Have you already checked out Gran Paradiso?  What did you think?  Give us your take by adding your comments below.
Tags:  Mozilla, Alpha, Ara, AR