Just some observations and suggestions, in no particular order:
1) It would be nice to have the popup for Custom Build, Browse & Buy and Learn buttons be the correct size so we don't have to scroll left or right to see the entire popup page.
2) I like the dropdowns from the new menus along the top. I think it would be good to have a Browse & Buy button under each of the listed options though. For Instance, I click on Guitar Bodies. The dropdown scrolls and Standard Stratocaster is the first on the left with pic and button as a link to the Standard Stratocaster information page. It would be good to see a Browse & Buy button right underneath the first button. Clicking the Browse & Buy button would take me to the In Stock Standard Stratocaster page.
3) Much better cart graphic than before and it's not as intrusive on the pages when I open it. I'd like to see the number of items in my cart though. Maybe you could overlay a counter on the top of the shopping cart basket?
4) I like the Showroom Beta. Nice navigation and the filtering works well. I did notice that in some cases the selections I had made for a filter, Solid for Construction for example, were not remembered when I scrolled that filter open again.