Almost all comic scan formats come in either CBR or CBZ format. These are really just RARed or ZIPped image files. There are a variety of viewer programs but the one I've come to use is Comix.
Comix is about as intuitive as a program can get. It automatically unpacks the archive and all you have to do is flip through the pages. There are some rudimentary keystrokes to display the pages in full-screen mode, actual size, fit-width, and as double page spreads.
To install Comix,
sudo apt-get install comix
To read the CBR files, you also do need to install a RAR unarchiver. To do this,
sudo apt-get install unrar
After that, you're good to go.