As far as I can tell there isn't full Java support or it's damned buggy. Plus their Javascript support seems to be totally gone. It still seems a tad slow.
On the bright side there is a skin to make it look like Netscape4.X, it's a hell of a lot faster than PR1 and pages load up pretty damn fast once the initail connection to the site is made and starting up PR2 seems faster.
Hope they get it right, itching for full style sheet support