If you install CyanogenMod on the Nook, it's perfect. Of course, the dual core isn't as responsive as today's quad-cores; nor are the graphics outstanding. For the price you pay for, you're getting a serious bang for your buck. By all means, the tablet is NOT slow or will you notice any problems when using it.
It runs perfect with CyanogenMod. Remember to install CM10.1 Release Candidate (RC), as there is a major issue with CM10.2 right now.
If you're buying it just to play around/test with, no worries. Although I think it can do more than just that. Of course, that's still not a problem. Go ahead, it's a great way to start developing into Android.