Some issues I've noticed with DNN 6.0 Beta 1:
1) font sizes on the home page were off (before & after)
2) Initial Logon panel was blank, aside from the resize control. Resizing didn't force it to appear, but a page reload may have brought up the controls. However they were misaligned, and when I would hover over the OK button the button would jump to a different place (i.e., on the previous line?). Try as I could, I could not click the OK button! Hitting the return key worked for me though fortunately. See this and this. On subsequent logons, the controls appear, but still misaligned.
3) Control panel never loaded admin & host menus, even after multiple reloads and dinking around on the site. See this. I was focused on other aspects, but think I couldn't initially interact with the control panel - maybe due to lack of hover style change, the buttons look like static images. Host and Admin menu buttons (in the page top control panel) still don't display right the next morning.
4) In IE8, there is a javascript error, if one looks at page errors: see this
5) Trying to select the Manage Panel causes it to jump around. See this. If I move the mouse just a hair higher, the manage menu disappears (see this, note cursor is now an I beam) - I can never get my mouse into the dialog - arggg!!!
6) Admin screen, for host appears wierd, with duplicate images. see here and here.
7) Add page page also looks wierd. See here.