(This is not meant to be a detail review, just a few points that interest/annoy me.)
Chinese file name is supported, but for EPUB format books a CSS has to be added so that it will use the built-in font for displaying Chinese, or otherwise you’ll get ‘????’. For PDFs it relies on the built-in fonts for displaying Chinese.
Nook uses Adobe ADE (Adobe Digital Edition) to display PDFs and EPUBs. If you choose a font size that is too big for a page, it starts to reflow your document. The result may not be what you want: (i) words can be broken half way depending on the PDF, and (ii) formulas would be unreadable.
(There are 6 font sizes for you to choose from, but Nook only maintain a global setting which means you cannot have small for one file and medium for another—you must switch the font size every time. [Mine is on firmware ver 1.5])
The USB mode is good—no software needs to be installed on the PC side (although you may want to install Calibre—a free ebook management software)
After you have hacked (root) the Nook there’s another option for viewing PDFs (APDFViewer). When opening a PDF file it will ask you which one to use.
APDFViewer allows landscape mode. You need to crop the white margins of the PDF, though, because by default it does “fit to page" in portrait mode and “fit to width" in horizontal mode. Other zoom levels exists, but is limited to 25%, 50%, 75%, 100%, 125%, 150%, 200%, 250% and 300%. There’s no “panning" from the touch screen and buttons provided are minimal (from left to right: zoom level, rotate (upright or 90-degree clockwise; edit: long press for clockwise), page up/down (tap and hold for page selection slider) and quit. (as of ver 0.0.3)
As for cropping the PDFs, pdfscissors is free and nice but will leave a watermark at the first page and the last page (*edit, 13 Oct 2011: the watermark is removed in 0.0.2). PDFill PDF Tools (8.0) somehow produce files that Nook has trouble determining the borders. pdfcrop script is another option. (edit: Briss also works—thanks Ke Wu for pointing it out)
(edit: Documents made with LaTeX do not look so good because the Computer Modern Roman font does not look good on screen—the strokes tend to be thin.)
Instead of making a lot of edits there’s more comments here.