Nooks and Fires have about the same viewable area as a paperback book has printed text area. They're just fine for reading. iPads have about the same viewing area as a Trade Paperback book. That makes them a bit easier to use for other tasks beyond simply reading or casual surfing. If you need massive (relatively speaking) viewing area, then maybe a Samsung Galaxy or Acer eee Slate.

It all depends on what you intend to do with it.

Now as to Androids "Failing", I'd hardly call the 6-8 million units (depending on who you use as source) sold as a fail. It's still 20-40% (again depending on your source) of the total tablet market.

Not a fail. Not great, but Not. A. Fail.