Read this: http://pthree.org/2007/08/12/aptitude-vs-apt-get/
Back story: Yesterday someone on SILC asked about the difference between aptitude and apt-get, and why to use one over the other. I haven’t looked at the source code so could only provide reasons based on anecdotal evidence. The link posted above contains a concise write-up by Aaron Toponce on the difference between these apps.
