I bought a Nook last year and ended up getting rid of it. The PDF rendering sucked, and their customer service is worse.
You may not care about rendering Mathematical Symbols (see below), but if you read on, you will realize that B&N's so-called 'tech support' sucks pumice.
They claimed that the Nook supports the ePub standard, but it really doesn't do so fully. I put a couple of freely downloadable mathematical ePubs on it that had mathematical symbols like script R (used to denote the set of real numbers), and those symbols rendered as question marks. By contrast, open source e-Readers (like fbReader for Linux) rendered those symbols just fine.
Since the ePubs in question were freely downloadable, I emailed one to the Nook technical support address saying 'here is an example of something that doesn't render correctly. Please forward to your technical people and ask them to fix this in a future firmware release.' The first few tiers of 'script monkeys' who replied were obviously looking for a pre-canned response in their script monkey database that might make me shut up and go away. After about two weeks of email back-and-forth I finally got a reply from someone who seemed to understand my question.
His reply?
"We didn't sell you the epub with mathematical symbols in it, so it's not our problem."
I'm sorry, but if the set of grad students who wrote fbReader can figure out how to render mathematical symbols, and give their software away, your so-called 'professional programmers' ought to at least match their performance if they are going to charge me for their work.
You might consider the Ectaco JetBook. I've heard good things about it, and when I sent them the same epub, the first guy that replied said 'yeah, I loaded it onto my own JetBook, and I can see the script R.'
Again, you may not care about mathematical symbols, but you might care about tech support and customer service.