The original poster seemed to be asking about Color Nook FOR Coby Kryos. But the responses, from what I can tell, are along the lines of Color Nook VS Coby Kryos, understandable given the subject line. I downloaded the Nook android app onto my Coby Kyros a few days ago and have yet to read a word from a book. And, from my experience so far, I do not expect to.
The problems might be specific to the Coby, but I have not gotten past the registration stage with the app. Here is a summary of my first three tries. 1) I made some typo deep into the third page of registration questions, and, hoping to correct it, hit the "Back" button on the Coby. This took me all the way back to the Nook splash screen with the "Register" button. 2) Starting over from the top, I made it further, entered an email address and a password. After entering still more information, I got a message that my chosen password was in the wrong format. There was no description -- either before or after entering that password -- of what constitutes the correct format. 3) I tried again, repeating most of the registration info I had typed on the first two tries. My revised password was also rejected, but more quickly and more precisely. More specifically, it told me I needed a password with from 6 to 8 characters. I had entered a 7-character password.
Also on all tries where I got as far as a password question, I was prompted for the secret answer ... without being asked the secret question. In both cases, I was able to wriggle the prompts so that it took me to another page with the question. But I can't remember exactly how I navigated that.
Guess I never really navigated the question, even if the error was about the password. When I took another try a few days, the secret question WAS visible above the prompt for the secret answer. Here's what I think was different: I was holding the tablet in portrait mode, rather than landscape as in the first two tries. So I was able to register. Before I could read a book, though, I would have to pay for it, and it would still take two phone calls to B&N and three trips to the B&N website from a desktop machine before the institution would take my money. I had some trepidation about those desktop trips because the the site had come close to crashing my browser earlier. But the only way to redeem my certificate was by logging in on the conventional site. Because a B&N staffer was on the phone guiding me, I braved the website. I was able to log in, and reluctantly entered a credit card number, even though I was going to pay as I went with the gift card. After the desktop exercise, I was ready to try it on the Kyros, but the tablet had fallen asleep. After some indecision, I let the support guy hang up, and revived the tablet. Bad idea. This time, when I tried to Confirm my purchase, I got the message: 'No default credit card...' and a recommendation to go to the desktop site. Went back on the desktop and my card was indeed still on file. Called back and the second support guy was surprised, but suggested it might take an hour or two for the information to make it to the mobile side. In an hour or two, I'd be at work, so I did not get to check for 10 or 12 hours. And the explanation sounded lame, given that a certain online retailer (known especially for the Candle, brindle, some gadget that lets you read books) seems to register info across all of the Internets at once. Ten hours later, I tried again. Same credit-card related error. Decided to try again this morning. Again, 'No default credit card...' Went back to the desktop site. It still had my credit card. But wait. If I go to My Account,' 'Account settings,' 'Manage Credit Cards,' I see the card, and it's the only card. But it was not the DEFAULT card. Made it the default card, and I could purchase and confirm. Went back to the desktop site to ensure that the money came out of the gift card and not the credit card. That at least is the default. One remaining, smaller problem. I had downloaded several samples, and it does not look like I can delete them from the tablet. In another forum (think it was official Barnes & Noble), I saw the advice to delete it from the desktop Web page. I did that with one thumbs-down sample, but it still appears on the Coby after relaunching the app.
Bottom line, I am reading from the Nook app. It took some time and aggravation though.