For some reason, the Aptitude version in Ubuntu 10.04 is 0.4.11 while Aptitude already reached version 0.6.2.1. The most important feature which misses from Ubuntu is Aptitude GTK - a GUI for Aptitude.
But you can install an updated Aptitude version which comes with Aptitude GTK from a PPA (available for Ubuntu 10.04 and 10.10):
sudo add-apt-repository ppa:yofel/ppa && sudo apt-get update
sudo apt-get dist-upgrade && sudo apt-get install aptitude-gtk
Note: the commands above use apt-get and not aptitude as one would expect for a post about aptitude because Ubuntu 10.10 won't come with Aptitude by default.
To run the GTK interface for Aptitude, all you have to do is press ALT + F2 and enter: