I bought the Nook Color for the same reason. The Nook Color PDF reader is a very capable viewer. I didn't want the Nook version of Android so I bought one that was already rooted with CyanogenMod.
I'm mostly happy with it for reading PDFs. Like any tablet-sized reader you will have to pan. You can view the pages in portrait mode fully zoomed out but it's hard to read that way. I read in landscape and just pan the document a bit. I'm finding more authors are publishing to PDF using one column. In those cases it just work. Pinch-zooming works but the text rarely (if ever) re-flows the way web pages do in Chrome.
I don't like the Adobe file browser on Android, though. It adds every PDF on the SD card to the master list. It's a giant scrollable list with each folder path as a section separator. I would like the option to toggle between hierarchical folder view and list.
I tried using Calibre to convert some PDFs to ePub. Two-column PDFs have been a disaster. I rarely get anything that's usable. YMMV. I decided to stick with PDFs (or .ps files I convert to PDF).
Using Chrome to read web pages is mostly workable. Strangely, clicking an HTML file in the file manager doesn't launch the regular Chrome browser. Rather you get the "HTML Viewer". It's mostly Chrome but has no open dialog or access to bookmarks (AFAICT).
As an Android device it's quite functional. Most market applications install without a problem. The one I have problems with are those for which the Download button doesn't appear. I haven't chased the issue down yet. Not sure whether it's a Cyanogen issue.
Google Books works great but you have to have internet access to read the books. Just goes to prove Android is really designed to be an always-connected OS. FBReader, on the other hand, just works.
As you can tell, it's no iPad in terms of "It Just Works". In sum, as a PDF reader I'm mostly happy with it. All the other features are bonuses. The issues are mostly irrelevant.
Lastly, if you check E-Bay or B&N's website they sell refurbed Nook Color's for $199. For an extra $50 you can get the extended warranty (if you're into those). For the same $249 for a new one with 1-year warranty you get a unit with a 2-year warranty.