Laputa is... interesting.
Not a badly designed reader, though it has its faults. So does Aldiko, my personal choice, and every other reader I've found (and I keep on trying any I find looking for something to compare to my readers on past devices, uBook and palmfiction being my Windows mobile and Palm preferences).
If you want to read books legally, and I have no authority to say whether you should or shouldn't, Laputa is not the app for you as the vast majority of the books it offers are offered illegally. On the other hand, if you do want to pirate books, it isn't terribly hard to do so and load them into most other reader software. Laputa just makes that process invisible to the user.
And on topic, I saw how much space the Nook software took up in my phone's memory and instantly uninstalled it. I also didn't find a "night" setting in my short time checking it out (with an AMOLED screen, night setting is a huge battery saver).