The rule of thumb is if you have the new PBS channel on your Roku, you'll be getting the update. If not, you're out of luck. I was one of those that was out of luck, hence the mailman delivering my new box today.
Sooo, this is weird, I have two Roku XD's and one got the update and the other didn't. When I tried to manually check for an update, it said it already was up to date. Apparently Roku must be rolling it out on some type of schedule according to serial numbers maybe?
On a side note, I do like the new interface. No more scrolling through a long row of channels. Much easier and nicer looking. I would even say the roku works a little better now, not so much buffering.
My ROKU 2 XS still hasn't received the update, but receives the new PBS channel.
On the ROKU 3 I love the new interface, but I wish it had 5 columns instead of 3 and the "ad" was removed. I also would like to group the channels by "cooking", "live streaming", "news", etc.