There have been discussions on this and Nallia wrote an extensive comparison on many apps that first came out. Many, if not most free apps on Android have ads. They often feature pay for versions without the ads. Angry Birds on the NC is in HD, optimized for the NC's screen. The Andoid version is not. This is up to developers. And, I don't get the question about them trying to make this better. Apps enhance the experience, some are specific to the NC and not found elsewhere. The NC is primarily an ereader, but with some tablet functions. Apps like quickoffice pro, ezpdf, and so on just add to the functionality. You decide if they are worth the money if there's a fee.
There are few points to consider when answering such question:
1) There is very high volume of piracy on Android, so Rovio decided to put ads in it and release it for free, in other words the revenue is paid by sponsors, not by consumer in exchange for slightly annoying ads. If not for piracy, the price would be the same as in any other app store.
2) NOOKColor is a tablet, developing for tablets is more expensive resource wise.
3) B&N does not allow ads in apps, thus the only revenue stream is pay-per-play model (a.k.a paid apps)
I hope this helps to understand the business model developers have to choose when publishing for NOOK Apps, so they can have decent ROI.
I don't understand how anyone can complain paying $2.99 for hours of enjoyment. I think it is quite a bargain. The games that play on other devices that have advertising are very annoying. I think it is totally worth the price we pay to be commercial free.
You can't get angry birds for free, yes you can get the free version but it's not the same.
Everything free on your android phone is just a version, the paid app like on NC are the same that are in your android market.
Why is everyone so darn cheap over stuff?