I am running Leopard Server and I have found that there are some problems with it: There is no sound coming out of it, I am not allowed to scroll my mouse 360 degrees (mouse not detected), and (most importantly)
These two are normal and expected. We don't currently have an audio driver for OS X guests, and we don't currently support horizontal scrolling (vertical should work, though).
I cannot drag & drop files between host and guest, so I am forced to resort to getting files to an external hard drive
I'm not sure drag-and-drop is currently supposed to work. Another alternative would be a HGFS or network share.