I had the app on my iPad, till I obtained a Kindle, and it worked really well, with around 80 titles.
You can keep titles in "Cloud", and select those on the device more easily. (on the Kindle you can split into "Collections")
I've got the kindle app on my samsung android phone and it works fantastically! If i read up to a certain point of a kindle book on my phone, when I go to the kindle program on my PC it opens at the same page. No dramas so far. Remember. reviews are always negatively skewed because upset customers are much more likely to make noise than satisfied ones. You can always delete it if you don't like it.