Yes, the back button on your remote will take you back to the home screen of the particular library you're in (showing your On Deck, Recently Released or Added, and random discovery recommendations for that library). Unfortunately if you've navigated into a particular movie, etc, the back button does exactly the same thing (take you all the way back to the library home instead of to the screen you were just in). So if you like to engage sort and filter options and maybe browse a bit to arrive at your viewing choice, be prepared to either forego opening the movie, etc. to read the description or watch a trailer, or know that if you do you'll have to take the extra steps of going from the library home/discovery page it sent you all the way back to, into the library itself again (where at least your previous sort/filter options are preserved), and then scroll all the way back to where you had previously left off.
When 2.0 was released there was a comment in the release notes about the back button being a known issue, however it's not entirely clear to me that what I'm describing is the issue they were referring to. (On another thread where I mentioned this issue someone else said that the back issue had already been fixed with 2.1). So I don't know if this is a bug they are still working on or if this is how they think back should actually work from inside the movie, etc. I hope someone will clarify though since this + the inability to create and add to queues in the music library are my only real problems with the new UI.