It's great for those of us who would use the Kindle app, but it has also led to some 1-star reviews in the Android market from people who are upset because they can't remove the app from their phone.
Despite that, I think it was a smart move.... From Amazon's perspective, the ones complaining about it probably weren't potential customers anyway. But by having it as a core app, they catch the attention of potential ebook customers right out of the box.