Nook was the second major entry as a consumer e-reader but lost because they didn't think about user experience. You went into the store to download and buy ebooks? Convenience anyone? No? What about the lower secondary color screen before the color came out. Why? Then it was a rootable android device, not so bad, but they just didn't focus on what was important. Their online book store sucked compared to Amazon. They just couldn't compete. Also had a mortar business tying them down, but that isn't much of an excuse because Amazon had a ton of other stuff on their plate. Seriously, from what I hear from someone that interviewed- they had no clue what they were doing on the online side and wanted to reinvent it but didn't know how. It has been a huge fail.
I like their mortar stores but I haven't shopped there is ages, so I imagine that others are the same. They need to drop the nook or at least completely reimagine it and rebrand it (nooks are for english muffins), start up a second online team completely physically separate from the current one hiring top talent for UX and focus on a non-backlit color e-ink screen for whatever the rebranded ereader is called. The mortar stores aren't cheap to run either, and most stores are way too huge for the amount they sell. That needs to change also.
Basically, they need serious, serious help. It is a shame that B&N used to be the epitome of a bookstore, but now it is seriously flailing against a company that sells more other stuff than it does books. But who knows, maybe taxes will kill the Amazon giant.