Doesn't really have it's own plot. It mostly deals with backstory of Casino Royal and even picks up exactly where it left off, so definitely watch Casino Royal before going to Quantum of Solace. Otherwise, it's another action packed Bond movie based on Bond getting revenge
I saw it in IMAX and then in normal theaters and IMAX is definitely better. Not only is it going to be bigger, but they didn't reformat for the widescreen of normal theaters so you actually have detail being cropped out.
The movie is dark and looks into morals and society and doesn't have a happily-ever-after ending which makes it one of my top favorite movies.