This is turning out to be one of the best betas I have seen in quite a while. And I have looked at a few.
Other than general polishing I only see a couple issues that really need resolving before the final.
1) The message.mint problem I mentioned in another post. Currently you won't get the nice boot screen if you have a separate /boot partition. There is an easy work around listed in my other post but suspect most of your target audience will not be able to work it out.
2) This one is a bit more complicated. This problem is showing up on 3 different machines. Different motherboards, disk arrangements, amounts of ram, and BIOSs. The only thing they have in common is Intel processors. And then not the same one. Two single core and one double core. The problem is when the system has been running and being used for 3 or 4 hours it gets slower and slower. It seems to show up first in Firefox but I don't know if this is the bad guy or not since Firefox is a bit of a resource hog to begin with. It gets to the point that you scroll with the mouse and have to wait a second or two for the screen to respond. Or you type and the key board is so far ahead of the screen it becomes unusable. You can see the same thing in Kate, Open Office, and Konq. Though not as bad as in Firefox. On boot up it is not quite as fast as Kubuntu, but it is close enough. It is only after a number of hours of use that this problem begins to show up. I am not running out of memory. The system is using only slightly more memory after 4 hours as it does shortly after boot-up. I strongly suspect a resource depletion problem but haven't been able to put my finger on it. If others are having this problem too this is a real show stopper. If you need any further info that I might be able to supply, feel free to pm me.
On your way to an excellent release!