Aldiko has been one of the most popular Android apps since it originally came out on Android in 2009. They have been teasing an iOS version for over a year and have finally released one for the iPhone.
Aldiko for iPhone allows you to download thousands of open sourced e-books for free and allows you to import in your own EPUB and PDF files. The app is compatible with Adobe DRM, so you can import in your purchases from other online bookstores.
One of the most exciting aspects about Aldiko for iPhone is that it is fully compatible with your local libraries e-book collection. You can automatically detect what library is closest to you via location search and input your login credentials. If you live in the US, the library aspect is really great, but if you live in Canada, or Europe there is a very paltry selection.
This app provides one of the best e-reading experiences on the iPhone. You can do all of the normal stuff like adjusting the font size, font type and background colors, margin, alignment as well as brightness to best suit your preference. The Aldiko Book Reader also supports night-time reading, which is very appealing to a number of people.
There app was just released today, and it not very optimized for the iPhone 6 Plus, since there is a lot of negative space on all of the screens. This should be remedied over time, but in the meantime it is worth the download if you have a large personal collection and dig importing in your own content.