The N2A card helps you run CyanogenMod, the open source Android firmware. It's quite popular, runs on many Android devices, and has the support of a sizeable development community. This card comes with a bunchaton of apps, including Android Market as well as the full suite of Google apps (what isn't included can be downloaded).
Much to my delight I was offered a free card earlier this week, so I of course installed it in my NookColor refurb and brought it with me on my trip.
I brought my NookColor with me to Boston because I wanted to test it. While I'm mobile I rely on my Android tablet far more than when I am sitting at my desk, and I've found there's no better way to find the limits of a tablet than to use it in place of my original Samsung Galaxy Tab as a work tool. Any tablet that can stand up to my moderate needs for reading, web browsing, Twitter, blogging, and following RSS feeds is at minimum a very adequate device. If it's cheap enough it goes from adequate to excellent (depending on the price).
Alas, N2A doesn't make the cut. As an Android tablet it comes a distant runner up to any and all of the budget tablets I've tested in the past few months. It has one huge defect that renders it unsuitable for me.
Battery life sucks. While any of the budget tablets will usually last a full day (or at least come close), when my Nook Color is running on the N2A card it didn't even make it 'til noon. That is simply unacceptable. What's more, I've also had the touchscreen go dead on me no less than 3 times today. That's an issue I've never seen before, and each time it happened I was forced to reboot the NookColor - costing me all the apps currently running.
But that's just me, and the issues I found might not be a reason for you to avoid this card. I'm looking at how well it works as an Android tablet, and the answer to that is poorly. But if you already have a Nook Color you are probably thinking about how you might get more out of this locked down ereader you own. You might even have already decided that you preferred an Android Tablet over an ereader.
In that case you might want to consider the N2A card. If you already have funds sunk into your NC and you're not satisfied, the N2A card might add enough value to make the $35 price tag worth it. It's certainly a better option than getting rid of your NookColor.