Anyone that reads on a mobile device, but doesn't dig Amazon's Kindle thing is probably using Aldiko. This is a super-popular ebook reader that supports EPUB, PDF, and Adobe DRM ebooks. It also works with titles rented through public libraries. You're probably going to wish it worked with more services because the new update looks excellent.
Aldiko 3.0 was designed with the Holo guidelines in mind. It's an almost perfect representation of modern Android design – someone on the development team may have actually channeled Lord Duarte himself. If you just glance at Aldiko 3.0, you might think it's the Play Store. The new update also includes some improvements to library organization and reading statistics.
The updated UI has only come to paid edition of Aldiko so far. It should arrive on the free app soon, but for the time being users who plunked down $2.99 are getting special treatment.