Well, I've installed the 32-bit version of Hardy on one of my machines. I LIKE IT! It's net perfect but it's getting closer. FireFox 3 is fast and clean. Man this is so much better than FF 2. Another BIG improvement is in Open Office. It too is much faster. In fact, everything is more responsive. Part of this is due to the indexing services being turned off by default now. Smart move Canonical! I always turn it off from the get go. When I'm searching for files on my HD I use Krusader's search feature. If you want to install Krusader from the command line it's: sudo apt-get install krusader.
Now for the only bug I've ran into so far... PULSE AUDIO vs. FLASH PLAYER. Now Pulse Audio is a good addition but it has issues because Flash Player isn't Pulse aware. The bug simply does this. Flash can't share audio output with any other application so if you are watching a flash video, don't plan to listen to a music player. You will only get sound from the first one that is launched.
I've recently read that 64-bit Hardy doesn't have this bug, but I haven't tested the 64-bit version yet so I don't know for sure. Also there are a couple of work arounds for bug for use with 32 bit, but the most common solutions (adding a special sound lib) seems to cause more problems than it fixes. Personally, I just won't listen to Flash files while trying to use other audio applications (until the developers fix the bug properly).