I find the Nook is not too good as synchronizing between devices. Unlike the Kindle, for example, which opens to the furthest position in the book that was last open, the Nook opens the book to the last position in the book that was opened on any device. So if you, say, open the Nook app on the iPad and it goes to page 153, then when you open the same book on the Nook STR it will try to go page 153, even though you may have read as far as 194.
I just try to leave the wifi off on my STR all the time so that won't happen. If I'm reading on my iPad or iPod touch I will find where I was in the book by myself.