I've been very pleased with my Nook. And I've seen the screen side by side with a Kindle 3, there's really not a ton of difference. Kindle's pearl screen is a bit brighter, but both are great.
I do wish BN would dump the separate library thing, but these days I mostly just sideload all my books onto my memory card, so it's less of an issue. My unit has been very reliable for the almost 8 months I've had it. My main complaint is short battery life. Otherwise, I really like swiping to turn pages. If I had more money, I'd consider a Sony 950, but Nook WiFi was a good deal at $149, even if it's been available for less since we bought.