I've not installed the Beta1 yet, but hopefully the mustard yellow nav bar in the admin/provider area was redone, is my main gripe as well as Modify Product added back to the Invetory menu, I think I go to that text link the most.
Just a note, I see alot of feature requests of mods that already exist for 3.4.x to 3.5.x versions of X-Cart on either my site:
http://www.cart-Lab.com
FunkyDunk's:
http://www.prodynamix.co.uk
Groovico's
http://www.firetanksoftware.com
Carrie's:
http://www.bcsengineering.com/store/catalog/
Like the sitemap, product sorting, etc.